Telescope: Atrotech AT 72ED II 72mm aperture 430mm focal length f/6 Mount: Iopteron CEM 25 hypertuned Exposures: 60 subframes @ 60 sec each over 1 nights for 1 hour of integration; ASI533MC-P; UV/IR filter Processing software: Siril Location, Bortle, and Date: Washington Crossing Park soccer fields; Bortle 6; October, 2025 Description and Story: Comet C/2025 A6 (Lemmon) is a long-period, non-periodic comet discovered on January 3, 2025 by the Mount Lemmon Survey in Arizona. It follows a highly eccentric, retrograde orbit, meaning it moves opposite the direction of the planets, and it likely originated in the distant Oort Cloud. The comet reached perihelion on November 8, 2025 at about 0.53 AU from the Sun and made its closest approach to Earth in late October 2025 at roughly 0.60 AU. Although it was extremely faint at discovery, it brightened far more than early predictions, reaching around magnitude 3.5–4 at peak, making it visible to the naked eye under dark skies and a strong binocular target. As it approached the Sun, heating drove strong outgassing that produced a prominent coma and both dust and ion tails, with spectroscopic observations revealing typical cometary gases such as carbon-based species and sodium. Scientifically, Lemmon is valuable because comets like it preserve primitive material from the early solar system, offering insight into its original composition and the processes that shaped planetary formation.
A recent article in Scientific American about the Celestial transients piqued my mind. To quote “Transients are astronomically sized objects that change on human timescales—in seconds, hours, days. Transients, which are astronomical objects that appear suddenly from nowhere and usually disappear soon after, contradict the standard truth that the universe changes predictably and slowly over billions of years.” I will describe some transients and the telescopes to track them.
Examples of transients are fast radio bursts, gamma ray bursts, supernovae, core collapses, magnetars etc. Of these, supernovas are well known as they indicate a dying star which sheds all the accumulated elements due to an explosive surge as a pushback against gravity. Supernovae cook higher elements in the periodic table. A Supernovae’s brightness outshines a galaxy and lasts for a few days to months before dying. These shed elements will be inputs for formation of the next generation of stars, like our Sun.
When a massive star collapses on itself, its electrons fuse with the nuclei of its atoms until the star is made mostly of neutrons—a neutron star—and it shrinks in the space of one second from a radius of about 6,000 kilometers to about 10 kilometers. The collapse causes a shock wave that breaks out and minutes later the star is as bright as 10 billion suns. It fades over months. This is the birth of a neutron star. Our Sun will not end up being a neutron star or a black hole. It is comparatively less massive.
Another example of transients is Magnetars which existed only in theory until they were observed in 1998. A magnetar is a neutron star that rotates very fast in a few milliseconds. The magnetic field is very high. Our Sun’s magnetic field is about 10 gauss. Comparatively the strength of Magnetar’s magnetic field is 1000 gauss. Hence the name Magnetar. It is highly unstable and reconfigures itself quickly.
Now that we looked at a few examples of transients, let us look at the kind of telescopes and the facilities needed.It needs a different type of telescope to look for transients. The discovery telescopes, as they are known, need to observe a large swath of the sky in one shot. A wide field camera is required to detect such images. An example is the 48 inch Samuel Oschin Telescope at the Mount Palomar observatory. It is part of a facility called the Zwicky Transient Facility, named for the famous 20th century astronomer Fritz Zwicky.
The Zwicky Transient Facility consists of 3 telescopes – one is the 48 inch which is the discovery scope, next is the 60 inch which is used to follow up on the finds of the 48 inch. And further follow up is done using the famous 200 inch at Mount Palomar in Southern California. The 48 inch telescope is fully automated which scans wide parts of the sky every night. It is what is referred to as industrial scale operation – night after night with almost no human intervention.
Although the 48 inch dates from last century, everything else about the telescope is modern. The wide field camera which captures 47 square degrees of the sky in one shot. And each shot lasts about 30 secs. There is a robot arm which places the filters in the path of the camera to capture a part of the spectrum. At that speed, it requires 2 nights to capture the whole northern sky. The whole electronics are maintained at a very low temperature of 100 degree kelvin using liquid nitrogen. To minimize any hardware related noise.
Southern skies are still unknown but there are other telescopes like the new Vera Rubin telescope, located high up in the Andes mountains of Chile, which does some of the same functions. In addition, it does a lot more.
Software then compares the images from 2 days back for the same part of the sky to detect what is different. If a difference is detected then it is likely to be a transient. But first, any spurious streaks like satellites or meteor showers should be eliminated. If genuine, an alert is generated for further follow up. Machine Learning is used for classification of events. All the data and the alerts are uploaded to Alert brokers so that different groups of scientists can filter out what is of interest to them.
Astronomy is as much of a data science as it is just peeping into a telescope. Leading to “Time-Domain astronomy” in which the skies are photographed continuously in the night and interpretations of data are made thereof. And Python is the language used extensively in astronomy (Information Technology professionals, please note).
Since its inception in 2017 Zwicky Transient Facility has discovered around 10,000 transients. And more importantly, its comparison software and the alert broker infrastructure formed the basis for the recent Vera Rubin telescope in Chile. This seems to be the trend for broader survey telescopes. They scan the skies and store the data so that astronomers can download and interpret them.
I don’t think it would be wrong to label the current era as the early dawn of the space age. Hardly half a century has passed since the first rockets left our atmosphere. Even in the early stages of space exploration, however, orbital clutter has become a serious issue. Thousands of active satellites, discarded boosters, destroyed machinery, and other pieces of orbital scrap are slowly clouding up our skies. As of now, actual rocket launches remain largely unhindered, but the debris clouds’ impact on astronomy is already beginning to show. Some studies indicate that 10–30% of twilight survey images are affected by satellite or debris streaks. Even if orbital clutter isn’t actually blocking out our skies in some dramatically dystopian fashion, it increasingly damages the data that we collect. Although stacking techniques can help mitigate the impact, the quality of Earth-based astronomy will only deteriorate if the orbital clutter problem is left unchecked. This poses an obvious question: if the problem is already noticeable and continuously worsening, why aren’t there any measures to prevent it?
The problem is not a lack of awareness but a lack of governance. When the first rocket launches were happening, the amount of space debris was low, and few would have recognized the eventual potential for such an issue. Consequently, no preventative measures were put into place. As government-led launches slowed and the private sector became more prominent, the pace of orbital expansion increased faster than existing safety and sustainability frameworks could adapt. The amount of space debris will keep increasing without regulatory systems that protect astronomers. With that said, it’s important to explore multiple potential solutions because this issue is not as straightforward as it might seem.
Simply cleaning up the existing objects and instituting systems to efficiently remove future ones seems to be the most direct solution. Unfortunately, this process is much easier said than done, and the cost to remove even a few large pieces of debris is simply not worth the trouble. The majority of debris is small and difficult to locate and discard. Cleanup efforts would be unable to keep pace with the speed of new launches. Therefore, prevention is the only remaining solution. For example, a mandate that all launched satellites must have a plan to deorbit once they have reached the ends of their operational lives. This could be achieved through controlled reentry or gradual descent mechanisms that lower the satellite’s orbit until atmospheric drag causes disintegration. Mandated safe fuel disposal to prevent explosions would also be a significant help, drastically reducing the creation of smaller debris pieces. Some system of accountability would also be prudent: for example, making the owner of the rocket responsible for pieces of debris above a certain size would take care of the largest, most obtrusive objects. Rather than mandating physical retrieval, making the owner of a launch vehicle legally responsible for large debris fragments would incentivize safer design and end-of-life planning without requiring impractical cleanup missions.
Astronomers have always had to work around obstacles to catch a glimpse of the night sky; after all, bad weather has been around for far longer than telescopes. However, such difficulties are predictable, static, and natural. The orbital debris problem is fundamentally different. It is man-made, preventable, and cumulative, and it will only worsen without deliberate intervention. Unlike atmospheric conditions or light pollution, orbital clutter cannot simply be waited out, nor can it be reversed. The most troubling aspect of the problem is exactly this lack of reversibility: there is no realistic way to “clean up” decades of accumulated debris after the fact. Prevention, therefore, is not merely preferable but essential. If action is taken now to limit further debris generation, orbital interference can remain a manageable inconvenience. In order to preserve the viability of ground-based astronomy, we must realize that Earth’s orbital environment is a resource worth protecting just as much as the atmosphere or night sky.
The Hubble equation is commonly used to estimate distances to distant objects emitting light. The observations by a number of astronomers, even before Hubble, recognized a relationship between velocity and distance of nearby objects. Velocity is estimated using spectral data from Cepheid and type 1A supernovas. The data is processed to estimate distances. Presently a linear statistical correlation to fit velocity with distance data creates a linear equation with a constant. The Hubble constant is derived from . This constant is used in a linear equation format to predict distances well beyond the distance the data was collected from. A statistical projection even with a strong verifiable relationship has questionable accuracy. This along with the looking into the past creates higher uncertainty as the projection goes outward. If the calculation for the velocity is not corrected for relativity then a hyperbolic error will be incorporated as a function of distance. The velocity of the emitter corrected for SR sets the speed limit of c and corrects for the clock differences between the observer and the studied object. The actual velocity and distance compared to the observer can be achieved by correcting local velocity with SR to the actual proper velocity . Create a modified Hubble equation or constant using the actual proper velocity to Earth or have two separate correlations with and :
1. The variable is the most important for estimating the actual distance. It produces a curved relationship that is very significant above .1c
2. Using corrected will be nonlinear out to the approach to c (the speed limit) but is not accurate for determining distance.
Summary Before modern telescopes the data without SR processing was fairly accurate within a reasonable± error of measurement. It is a different situation now because telescopes have a much greater range to view emitters at much greater distances and higher velocities. Relativity’s effect over the span of great distances and velocities is curved by γ and not linear. The Hubble tension indicates the deviation from linearity. The Hubble equation cannot exceed c. The purpose of the Hubble equation is to accurately project the relationship of velocity to distance within and beyond the established verified data from observations. We are limited at large distances to be able to observe Cepheid and type 1A supernovas. We can only derive velocity from spectral shift which should be corrected. The Hubble equation needs updating with data corrected by relativity. Making assumptions of distance significantly beyond the data is very problematic if there is not complete confidence in a corrected and accurate as possible. What is the impact of the corrected data on the Hubble equation? Is the linear hypothesis still valid or does it need adjusting or do we require multiple Hubble models?
Did Astronomers See a Star Explode Twice? Astronomers may have spotted their first superkilonova — a star that’s exploded not once, but twice. When massive stars die, they detonate in a celestial fireworks display known as a supernova. Often this leaves behind a neutron star — a dense, city-sized kernel. A spoonful of its material weighs more than everyone on Earth put together…more
-skyandtelescope
Explore Orion’s Massive New Stars with Binoculars Some constellations have all the luck. Orion not only has one of the most recognizable forms, including its signature Belt, but it contains two of the top 10 brightest nighttime stars (Rigel and Betelgeuse), three 2nd-magnitude stars and M42, the Orion Nebula, one of the brightest and most important star-forming regions in the galaxy. No wonder it sparkles on winter nights…more
-universetoday
The Sticky Problem of Lunar Dust Gets a Mathematical Solution Apollo astronauts discovered an unexpected enemy on the Moon. Fine dust, kicked up by their movements and attracted by static electricity, coated everything. It found its way through seals, scratched visors, and clung to suits despite vigorous brushing. Eugene Cernan described it as one of the most aggravating aspects of lunar operations…more
-universetoday
When Stars Fail to Explode Many stars die spectacularly when they explode as supernovae. During these violent explosions, they leave behind thick, chaotic clouds of debris shaped like cauliflowers. But supernova remnant Pa 30 looks nothing like that. Instead of the usual remains, long, straight filaments radiate from a central point of Pa 30 like trails from a sparkler frozen mid-burst…more
-universetoday
Space Mice Come Home and Start Families Four mice went to space as astronauts. One came back and became a mother. And that simple fact might matter more than you’d think for humanity’s future beyond Earth. On 31 October, China launched four mice numbered 6, 98, 154, and 186, aboard the Shenzhou-21 spacecraft to the country’s space station, roughly 400 kilometers above Earth…more
-universetoday
A Pioneering Study Assesses the Likelihood of Asteroid Mining A few years ago, asteroid mining was all the rage. With the commercial space sector rapidly growing, the dream of commercializing space seemed almost imminent. Basically, the notion of having platforms and spacecraft that could rendezvous and mine Near Earth Asteroids (NEAs), then return them to space-based foundries, was right up there with sending commercial crews to Mars…more
-phys.org
Finding runaway stars to help map dark matter in the Milky Way Hypervelocity stars have, since the 1920s, been an important tool that allows astronomers to study the properties of the Milky Way galaxy, such as its gravitational potential and the distribution of matter. Now astronomers from China have made a large-volume search for hypervelocity stars by utilizing a special class of stars…more
-phys.org
Einstein Probe detects an X-ray flare from nearby star Using the Einstein Probe (EP), astronomers have detected a new X-ray transient event, which turned out to be an X-ray flare from the star PM J23221-0301 located about 150 light years away. The finding was reported in a research paper published December 18 on the arXiv preprint server…more
-phys.org
NASA’s Chandra rings in the new year with the Champagne Cluster Celebrate the New Year with the “Champagne Cluster,” a galaxy cluster seen in this new image from NASA’s Chandra X-ray Observatory and optical telescopes. Astronomers discovered this galaxy cluster on Dec. 31, 2020. The date, combined with the bubble-like appearance of the galaxies and the superheated gas seen with Chandra observations…more
-skyatnight
Astronomers may finally have worked out what the Star of Bethlehem was, and why it behaved so strangely in the sky A group of astronomers believe they may have finally worked out what the ‘Star of Bethlehem’ really was, and how to account for its strange behavior, as described in the the Gospel of Matthew. The mystery of the ‘Christmas Star’, or the ‘Star of Bethlehem‘, is one that continues to intrigue historians of astronomy…more
-skyatnight
Scientists found a surprise in plumes erupting from this icy moon. It could be a major leap in the search for life Enceladus is a medium-sized moon of Saturn made up of a crust of water-ice and an ocean of liquid water below. The moon’s ocean is similar to those on Earth and is connected directly to Enceladus’s rocky core…more
-NASA
NASA’s Webb Observes Exoplanet Whose Composition Defies Explanation Scientists using NASA’s James Webb Space Telescope have observed a rare type of exoplanet, or planet outside our solar system, whose atmospheric composition challenges our understanding of how it formed. Officially named PSR J2322-2650b, this Jupiter-mass object appears to have an exotic helium-and-carbon-dominated atmosphere unlike any ever seen before…more
December 9, 2025 Meeting at Peyton Hall. December’s winds whirl over the ivy-covered gothic spires and gleaming contemporary towers on the Princeton University campus, where we’ll meet for our final session of the calendar year at Peyton Hall of Astrophysics. I hope you enjoyed the presentation by our young AAAP astronomers on their experiences with the Unistellar telescope at the October meeting. Youth will be in the spotlight again for the Dec 9 meeting. Our guest speakers are young researchers at Princeton and IAS who are studying the mysterious solar system bodies that orbit in the region beyond Neptune’s orbit at around 30 astronomical units from the sun. Recall our discussion at Peyton last month about the trans-Neptunian region, also known as the Kuiper belt, where shorter period comets such as the famed Hale-Bopp originated. The talk on Dec 9 will involve discovery of a significant new object from this region and implications for more. For additional information on the Dec 9 presentation please see Victor’s section below.
Following the first talk, we will have an Unjournal Club presentation by the AAAP Youth Group (Unistellar group), who on Nov 13 represented AAAP with knowledge and enthusiasm at the Stone Bridge Middle School Science Fair in Allentown NJ. Thanks go to Jason, Hassan, Mia, Rujula, Eklavya and Sarvesh for spearheading that effort. For the Dec 9 meeting, I hope that you will join in person at Peyton Hall. If you cannot be there in bodily form (as I, out of state for a couple months this winter), you may participate virtually through Zoom. See the link details below and on our website.
Thanks for a Colorful 2025! Our organization accomplished a lot during the past year, helping keep AAAP strong and vibrant with education, outreach, and science-social events. A big thanks go to my fellow Board Members, the Observatory keyholders and Outreach Committee, and the Website Design committee for making things click this year. Here’s a brief summary. Membership remained strong with over 210 dues-paying members. The Observatory at Wahington Crossing State Park was repaired back to full capacity electrically and electronically, with completion of the AC power rewiring project and JCP&L reconnection, and with Verizon fiber-optic high speed internet restored. We had a highly productive and engaging season of public Friday observing nights at Washington Crossing despite the challenges noted above. It’s difficult to estimate the total number of people who attended but it must be several-hundreds over the season. In June, we held a long-awaited but well-attended memorial for Gene Ramsey, fittingly at the WC Park Pavillion. We provided outstanding monthly programs at Peyton Hall (and via Zoom) with great guest speakers. The AAAP website was redesigned and re-coded and a beta version has launched, with cut-out of the old site expect here at year’s end. The AAAP YouTube channel is growing with a cache of well-edited recordings of our meetings at Peyton plus other activities (https://www.youtube.com/@amateurastronomersassociat1439). We successfully transitioned the fiscal functions to a new Treasurer. And following the remarkable donation to AAAP of a Unistellar EV Scope2 and the summer Unistellar student project, we launched a AAAP Youth Group helping drive connections and outreach to schools and others. It has been a fine year in AAAP, and I thank all of you who helped make it so.
A Winter’s Verse for Cold Nights. I close here with a brief poem to further set the mood as we approach winter solstice. — Rex
Sharp are these cold nights Moon and frost earth’s shadow share Stars beckoning beyond globe’s rim Waypoints and patterns for closing eyes. We dream in these wintry climes Wishing heaven to be our home Wrapped in misting clouds embrace Chilled yet warmed by lunar light. – Rex Parker –
The Universe in a Computer The December, 2025 meeting of the AAAP will take place in Peyton Hall on the campus of Princeton University on Tuesday, December 9th at 7:30 PM. As usual, the meeting is open to AAAP members and the public. Participants can join the meeting in-person at Peyton Hall or log in to the Zoom session as early as 7:00 pm to chat informally before the meeting begins.
The evening’s guest speaker, Jiaxuan Li, is a fourth-year graduate student pursuing a PhD in astrophysics at Princeton University. Recently, along with Sihao Cheng at the Institute for Advanced Study and fellow Princeton graduate student Eritas Yang, Li and his team discovered a trans-Neptunian object in an unusually wide orbit that challenges the Planet 9 hypothesis.
Options for Attending the Meeting You may choose to attend the meeting in person or participate via Zoom or YouTube as we’ve been doing for the past few years. (See How to Participate below for details). Due to security concerns, if you log in before the host has set up internet connectivity in Peyton Hall, you may need to wait in the Waiting Room for a few minutes until the host is prepared to admit you into the meeting. You’ll need to unmute yourself to make comments or ask questions. It’s polite, though not required, for you to enable your camera so other participants can see you. The meeting will be recorded and edited for posting to our club’s YouTube channel.
Join us for our “meet the speaker” dinner Mr. Li will be joining us for our traditional “meet the speaker” dinner at Winberie’s before the meeting. Our reservation is for 5:45 pm Tuesday, December 9th. Please contact the Program Chair if you plan to attend.
Here’s the anticipated agenda for November 11th, 2025’s monthly meeting of the AAAP:
(Times are approximate)
Getting to Peyton Hall The parking lots across the street (Ivy Lane) from Peyton Hall are now construction sites, unavailable for parking. We’ve been advised by the administration of the astrophysics department that we should park in the new enclosed parking garage off Fitzrandolph street and walk around the stadium and athletic fields. Here’s a map of the campus and walking routes from the parking garage to Peyton Hall. The map shows the recently completed East Garage. Not shown is an access road Sweet Gum that connects from Faculty Road to an entrance at the lower left corner of the garage. Stadium Road connects from Fitzrandolph Road to another entrance at the opposite corner (and higher level) of the garage. It’s about a 10-15 minute walk from the parking garage to Peyton Hall.
Featured Speaker: Jiaxuan Li jiaxuanl@princeton.edu
PhD Candidate in Astrophysics Princeton University
A Newly-discovered Distant World: The Dwarf Planet Candidate 2017 OF201 Astronomers Jiaxuan Li and Eritas Yang (graduate students at Princeton University’s Department of Astrophysics) and Sihao Chang (Institute for Advanced Study) identified a remarkable new world in the far outer Solar System: a dwarf-planet candidate named 2017 OF201, currently more than 90 times farther from the Sun than Earth. By combining observations spanning the past two decades, the team showed that it follows an enormous, elongated orbit that reaches deep into the inner Oort Cloud. With an estimated diameter of roughly 700 km, it ranks among the largest known objects on such distant orbits and is very likely a dwarf planet. Its extreme trajectory hints at a far larger, still-hidden population of similar bodies that may collectively contain about 1% of Earth’s mass. Intriguingly, its orbit does not share the clustering seen in some other remote objects—a pattern often cited as evidence for a possible “Planet Nine.” Continued searches for distant Solar System bodies will help unveil the true structure and diversity of this unexplored frontier.
Jiaxuan Li Jiaxuan Li grew up in Dingxi, Gansu Province, a small town in northwestern China. An amateur astronomer since elementary school, Li participated in several international competitions, including the Chinese National Astronomy Olympiad. He earned his undergraduate degree in Astrophysics at Peking University, then came to Princeton to pursue his PhD. He’s interested in a variety of topics in astronomy and astrophysics, mainly on galaxy formation and evolution, low surface brightness astrophysics, sky surveys, machine learning, and instrumentation. His current research examines the formation and evolution of dwarf galaxies through both careful observation and numerical simulations.
How to Participate (Links) Zoom& YouTube Live Amateur Astronomers Association of Princeton is inviting you to a scheduled Zoom meeting. Time: December 9, 2025 07:00 PM Eastern Time (US and Canada)
Join Zoom Meeting Topic: December 9,2025 AAAP Meeting-Prof. Cheng, Jiaxuan Li, Eritas Yang, Dwarf Planet Candidate Time: December 9, 2025 07:00 PM Eastern Time (US and Canada) Meeting ID: 824 8572 5475 Passcode: 136481 Join instructions
AAAP’s library of monthly meetings is available on the club’s YouTube channel. November’s edited meeting featuring a presentation “The Universe in a Computer” by Princeton University astrophysicist Dr. Romain Teyssier can be viewed at https://youtu.be/lqs7znI1nEg
A look ahead at future guest speakers:
Date
Featured Speaker
Topic
Jan. 13, 2026
Jamie Rankin Research Scholar Princeton University jsrankin@princeton.edu
Dr. Rankin will talk about her work as Project Manager for the Voyagers’ last gasp; observing the interaction between the solar and interstellar media as these spacecraft (still transmitting data since their launch in 1977!) leave the Sun’s influence. She’ll also speak more broadly about exciting things about how the Sun interacts with the interstellar medium and about the Princeton-led Interstellar Mapping and Acceleration Probe (IMAP) mission launched this past September.
Dr. Rankin’s role is described in a recent book “The Clock in the Sun” by Pierre Sokolsky.
Feb. 12, 2026
John Bochanski Associate Professor and Chair, Department of Computer Science and Physics Rider University
Dr. Bochanski has been connected to the Legacy Survey of Space and Time Discovery Alliance since his graduate studies more than 15 years ago. Rider University is part of the global effort using the Vera C. Rubin Observatory to map the optical sky. The Rubin observatory (formerly the Large Synoptic Survey Telescope, LSST) will capture more information about our Universe than all other optical telescopes throughout history combined. The observatory released its first images this past June. Prof. Bochanski will discuss the project’s history and discoveries.
Thanks to Nick Mellis for suggesting this speaker.
Mar. 10, 2026
Robert Vanderbei Emeritus Professor in the Department of Operations Research and Financial Engineering Princeton University
Prof. Bob Vanderbei will talk about stellar dynamics.
Apr. 14, 2026
Astronomer Berkeley SETI Research Center astrobrianlacki@gmail.com
September’s guest speaker Edwin Turner voiced his less-than-optimistic view of the prospect for discovering extraterrestrial life. Dr. Lacki, affiliated with Breakthrough Listen, a SETI initiative, recently submitted for publication a catalog of objects he and his team consider to be realistic and valuable observation targets. Dr. Lacki will talk about the catalog, “One of Everything: The Breakthrough Listen Exotica Catalog” and opine on the prospects of finding technosignatures and extraterrestrial intelligence.
Mr. Horgan will discuss his controversial 1996 book The End of Science, in which he argues that pure science, defined as “the primordial human quest to understand the universe and our place in it,” may be coming to an end. Horgan claims that science will not achieve insights into nature as profound as evolution by natural selection, the double helix, the Big Bang, relativity theory or quantum mechanics. In the future, he suggests, scientists will refine, extend and apply this pre-existing knowledge but will not achieve any more great “revolutions or revelations.” Shades of Auguste Comte, perhaps?
We expect to have copies of his book(s) for sale for the author to sign at the conclusion of his presentation.
As usual, the June meeting will take place in the planetarium at the NJ State Museum in Trenton. There will be no streaming of this live-only sky show and PowerPoint presentation. Topic to be announced.
Dr. DiMario will present a primer on astro-imaging.
Oct. 13, 2026
Becka Phillipson Assistant Professor in Physics Villanova University
Prof. Phillipson, originally scheduled to be October 2025’s guest speaker, is an unconfirmed prospect to try again in 2026.
As always, members’ comments and suggestions are gratefully accepted and much appreciated. Thanks to Ira Polans and Dave Skitt for setting up the online links and connecting the meeting to the world outside Peyton Hall.
Upon hearing of the Grand Re-Opening of the Nature Center in Washington Crossing State Park on Thanksgiving weekend, I wondered what AAAP could do to entice park visitors to view nature in ways above and beyond those offered by the Nature Center. You see, the Nature Center lies just down the road from our observatory, and their daytime activities were all slated to be indoors. We could open the Observatory roof and do Solar Observing, of course!
Word went out to our Keyholders to solicit volunteers to staff the observatory while the Nature Center did their thing. Once we had sufficient coverage for our telescopes, I invited AAAP members and Keyholders-in-Training (KIT’s) to join us. Then, all we had to do, was hope for clear skies. Nature provided that for us on Saturday November 29. And, what an incredibly nice sunny day we had!
I arrived around 0930 and made a brief stop by the renovated Nature Center to introduce myself and our event to the new naturalist, Joe Moore. We both promised to direct visitors to each others activities.
In total, we had six telescope set-ups in the field along with the observatory scopes. Our scopes were white light solar only and the field scopes had both white light and hydrogen-alpha capabilities. Later in the day, we pointed a few scopes toward at Venus and the Moon, for a change of scenery.
Five KIT’s appeared and I went through the set up and safety protocol for solar observing with our telescopes. The KIT’s were a big help in kicking things off in the morning. Two of them earned their keys to the observatory as they had completed their training.
While I was too busy to get a final head count (or photos), I estimate we had 35-40 visitors of all ages. In the crowd were a few Park volunteer employees and the executive director of the Washington Crossing Park Association. Also present were a local mom and dad and their daughter, who is currently studying Engineering at UC Berkley and working on a NASA planetary mission set to launch in 2030. They said they have visited our observatory off and on since their daughter was a little girl. Wow!
It was a busy day for all of us; there was never a dull moment. My wife, Jennifer, helped us close out the day, directing people to telescopes, answering questions and handing out brochures. Jennifer’s arrival provided Bill Murray and I a few moments to hang the Gene Ramsey memorial plague. While completing the task, we spoke well of Gene, remembering his contributions to the club and our personal lives.
As the Sun cast longer shadows and 1600 drew near, Jennifer and I took a walk up to the Nature Center. Jennifer spoke of bugs and flying squirrels (ask me about that sometime) and I talked of future club interaction with Joe and the Nature Center staff. Everyone agreed resumption of Nature Center operations was a good thing. Needless to say, Jennifer and I were deeply satisfied with the days activities.
Many, many thanks to all who came out to make it happen and observe the Sun.
Bubble Nebula NGC7635 taken by Michael DiMario Telescope: Celestron C9.25 Edge HD at FL 1645mm f7.0 Mount: Losmandy GM811G Exposures: 229 subframes @ 300 sec each over 5 nights for 19 hours of integration; ASI2600MC-P; Optolong L-Ultimate filter Processing software: Pixinsight Location, Bortle, and Date: Doylestown, PA; Bortle 6; August 22-30, 2025 Description and Story: The Bubble Nebula NGC7635 is a rich ionized hydrogen region (HII) in the constellation Cassiopeia. The “bubble” shape was created from the stellar wind created by the intensely hot central star (SAO 20575) and is within a giant, glowing molecular cloud. The Bubble itself is about 10 light-years in diameter.
Great Carina Nebula NGC3372 taken by Michael DiMario Telescope: Takahashi FSQ85EDX FL 455mm f5.3 Mount: Losmandy GM811G Exposures: 27 subs @ 30 sec each; ASI2600MC-P; Antilla Triband filter Processing software: Pixinsight Location, Bortle, and Date: Big Cypress, FL; Bortle 2; March 31, 2024 Description and Story: Great Carina Nebula is located in the southern sky constellation Carina located in the Carina–Sagittarius Arm of the Milky Way galaxy. The nebula is approximately 8,500 light-years from Earth. The nebula is one of the largest diffuse nebulae in Earth’s sky whereby it is four times as large as and brighter than the Orion Nebula.
This image taken in 2024, was reprocessed in Pixinsight. This evening’s session began with a 6-foot alligator very near my observing spot. Fortunately, it moved quickly back to the water. As darkness enveloped, the Everglades continued to be challenging with passing clouds, very large mosquitoes seemingly the size and whirring of humming birds, and python hunters with their large floodlights. The area of sky where the Great Carina Nebula was located was clear and was not my observing plan that night. However, NGC3372 was an opportunity to be taken that night as it was visible given its very low altitude. It was challenging as it was approximately 1-5 deg above the southern horizon, over far off trees and a field of many astronomers’ red lights. Imaging at this low of an altitude is equivalent to looking through approximately 11-26 atmospheres as opposed to 1 atmosphere at zenith.
Fireworks Galaxy NGC6946 taken by Michael DiMario Telescope: Celestron C9.25 Edge HD at FL 2350mm f10.0 Mount: Losmandy GM811G Exposures: 86 subframes @ 200 sec each over 2 nights with Antilla Triband filter; 90 subframes @ 200 sec each broadband over 3 nights for 9.8 hours of integration; ASI2600MC-P Processing software: Pixinsight Location, Bortle, and Date: Doylestown, PA; Bortle 6; October 3-18, 2025 Description and Story: The Fireworks Galaxy is located between the constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years. It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way. NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center. Due to its large number of star formation, it has been classified as an active starburst galaxy. However, this galaxy derives its name not from its star nursery capability but from the ten supernovae observed since 1917. The number of observed supernovae in this galaxy is ten times the number observed in our Milky Way galaxy, even though the Milky Way has twice as many stars.
Fireworks Galaxy was a challenging project given its small field of view (FOV) and thus imaging at native FL of 2350mm. The tracking of the Losmandy GM811G mount was outstanding. A bright Moon in early October forced the use of the Antilla Triband filter with remaining subframes taken in broadband (no filters) when Moon was absent.
3i/Atlas the Interstellar Comet taken by Daniel Mints Telescope: Meade LX200 EMC reduced to 1650mm Mount: ZWO AM5N Exposures: ZWO533MCPro – 35 subframes @ 60 sec each with Antilla Triband filter Processing software: Pixinsight/Lightroom Location, Bortle, and Date: Hillsborough, NJ; Bortle 6; Early Morning, November 18, 2025 Description and Story: Interstellar Comet 2I/Borisov—sometimes called “Atlas of the stars” for the vast journey it represents—made history in 2019 as only the second known visitor from beyond our solar system. Discovered by amateur astronomer Gennadiy Borisov, the comet entered the Sun’s neighborhood at an extraordinary speed and on a sharply hyperbolic path, clear signs that it was not bound to our star. Unlike typical comets shaped by billions of years of orbiting the Sun, 2I/Borisov came from the deep cold between the stars, probably carrying pristine material left over from the formation of a distant, unknown planetary system.
Messier 16 (Eagle Nebula) and Comet C/2025 R2 (SWAN) conjunction taken by Daniel Mints Telescope: Samyang 135mm Mount: ZWO AM3 Exposures: ZWO183MMPro – 240 subframes @ 30 sec each (LRGB mono captured) Processing software: Pixinsight/Lightroom Location, Bortle, and Date: Rockland, TX; Bortle 1; October 17, 2025 Description and Story: The conjunction of Messier 16 (the Eagle Nebula) and Comet C/2025 R2 (SWAN) creates a stunning celestial scene where two very different cosmic objects briefly share the same patch of sky. The Eagle Nebula, located about 7,000 light-years away in the constellation Serpens, is a vast star-forming region famous for the towering Pillars of Creation. These immense columns of gas and dust are nurseries where new stars ignite, shaping the nebula with intense radiation and sculpting its iconic form. The visual pairing of the fast-moving comet with the distant, majestic Eagle Nebula tells a story of two cosmic journeys: one fleeting and ephemeral, the other spanning millions of years.
“The Perfect Machine” is the name of a book written by Ronald Florence. It covers the design, construction and the installation of the 200 inch Hale telescope at the Mount Palomar observatory, close to San Diego in southern California. Recently I had the opportunity to visit Los Angeles and San Diego to be with family and friends. I spent a few hours at the Palomar observatory. Having read the book a few years back, I was thrilled to see the perfect machine.
The telescope was conceived by George Hale who was known for his research in solar astronomy, and importantly for constructing the 60 inch Yerkes telescope near Chicago and the 100 inch telescope at Mount Wilson near Los Angeles. He also cofounded Caltech. In 1928 Hale secured Rockefeller foundation sponsorship for the 200 inch telescope. It took a couple of decades before the construction could complete, just after the second world war. By that time Hale had passed away. The New York Times suggested that the new telescope be named in his honor.
The main part of a reflecting telescope is its mirror. Palomar’s mirror is 200 inches in diameter and was cast in Corning, New York. It is a very painstaking glass making process taking months to get it right. Heating sand in a rotating furnace followed by a very slow cooling process. Contemporary mirrors are not cast as a single piece. Instead they are composed of multiple segments, with each segment controlled by an actuator/motor. This is a scalable design but requires a lot of computing power to precisely move the actuators in tandem so that all the pieces work as one big mirror. Back in those days, such technology did not exist. Hence the need to cast it as one big piece. The cast was sent by a special freight train from New York to Caltech in California. Caltech has a polishing lab where the mirror was polished to very fine tolerances. The polishing work took longer since the work was interrupted by the second world war as Caltech turned to wartime research.
The next critical piece in the telescope is the mount. The telescope moves within the mount to point to a specific area in the sky and once locked to an object in the sky, to keep the telescope moving so that the object remains locked even as the earth below is rotating on its axis. It is like chasing a star as it is moving from east to west in the nightly skies. Today’s technology is different from what existed in those days. The current mounts are called alt-azimuth mounts. Such mounts move in two directions – one up and down vertically, other horizontally firstly to locate a given object and then to move with the object as it moves across the sky. This motion requires a lot of computing power and is the standard mount today on modern telescopes.
Back in the 1940s, Hale telescope was designed using the equatorial mount. A superstructure called the yoke (a Y or U shaped structure) is permanently aligned parallel to the axis of earth’s rotation. This fixes one axis of movement. The only manipulation required is to move the mount across the sky as the star moves through the night. This movement is called the right ascension. The telescope itself is mounted between the two arms of the yoke and is free to move in the vertical plane, called the declination. For a long time, I had a tough time imagining what the mount would look like. Pictures did not help me that much. When I saw the real mount, I could realize how it worked.
The picture given below is courtesy Palomar Observatory/Caltech. The thick tube in the middle of the picture is one arm of the yoke. The angle of this arm with respect to the floor aligns with the earth’s axis of rotation. The black truss structure extending to the top of the observatory is the telescope hung between the two arms of the yoke (the second arm of the yoke is behind the first arm, not visible from this angle). The telescope itself is free to swing up and down between the two arms of the yoke and is controlled by a motor. At the bottom of the truss is the mirror facing the sky. Towards the upper end of the truss are the secondary mirror and the electronics required to capture the images.
The yoke itself is connected to a horse shoe bearing which is on the right of the yoke. One motor moves the yoke on this bearing to position the telescope to a particular object in the sky. Once set, a second motor moves the yoke to track the object in the sky as the night progresses to dawn. This rotation of the yoke is on the axis which is parallel to earth’s rotation. These three motors are the key controllers of the telescope.
The following youtube video explains the mount in 2.5 mins while the second video explains the history of Mount Palomar design and construction. Both the videos show the detailed design of the equatorial mount and how it turns.
The whole structure of the mount and the telescope are housed in an outer cylindrical structure with a dome at the top. The dome has a slit on the top. This slit is open during the night for observations. The whole dome rotates on bearings at the top of the cylindrical structure. This rotation would position the open slit to the part of the sky which needs to be observed. Given below is the picture of the dome which I shot using my iPad pro. The dome is painted white to reflect the sunlight. The temperature inside the observatory needs to be constant so that the telescope remains in alignment all the time. The dark band at the bottom of the dome, but higher than the steps and the front door, indicates the track on which the dome rotates.
The whole mount, truss and the dome were designed by Russell Porter, who is a polymath considered as one of the founding fathers of amateur astronomy. Porter also contributed to the design of buildings at the Palomar observatory and Caltech campus. He made about 1000 drawings of the telescope and its related instruments and buildings.
The telescope works in the visible, infrared and ultraviolet ranges. It is a pretty wide range given the technology with which the mirror was built. Fred Zwicky used this telescope to detect supernovae. Maarten Schmidt discovered the first Quasar in 1963. These objects are very bright in the whole universe. But Schmidt’s spectroscopy revealed that the light is so red shifted which indicates that they are billions of light years away, formed during the infant stages of our universe. Now it is postulated that such objects represent supermassive black holes and the accretion disk of gases around them is the bright light we are seeing. Thousands of Quasars have been discovered since.
The telescope has been fitted with adaptive optics on its secondary mirror to modernize it. Adaptive optics is used to compensate for the distortions in the atmosphere which make the stars twinkle. The twinkle looks good in the sky, but makes the observations unsteady. Adaptive optics divides a mirror into smaller segments with each segment controlled separately by an actuator/motor. A reference laser is shot into the skies. The reflected picture of the laser is used to find out how much distortion the atmosphere is causing. Accordingly each actuator is moved differently to change the shape of the mirror to provide a sharp picture. Adaptive optics is a standard design for all modern telescopes.
It is a fascinating story of how the telescope was conceived, designed and constructed and the discoveries it made and the efforts to modernize it. My tributes to George Hale and Russell Porter, two of the most important people who built the Mount Palomar observatory.
Amateur Astronomers Association of Princeton 