Next meeting by Zoom on April 13 at 7:30pm.  While we won’t get together in person at Princeton’s Peyton Hall for meetings this spring, recent vaccination progress gives hope that it may be possible next fall.  For now AAAP will continue to meet virtually via Zoom.  We’re happy to receive the support and continuing interest from returning members as well as newer members.  The current roster (kept by club secretary John Miller) shows 125 total members, about one third of whom have joined AAAP in the past half-year. However, note that the last 4 Zoom meetings had an average attendance of 52 – this means that more than half of members are not showing up.  Please participate in the monthly meetings – we really want you on board.

With the professional speaker presentations that program chair Victor Davis and Bill Thomas have lined up (see the April guest speaker information below), I am confident that this important part of AAAP’s offerings to our members and the public are in great shape.  However, direct hands-on astronomy is another matter. With potential for winding down the state COVID guidelines as summer comes on, an important question is how to handle observatory access by members and future access by public this spring and summer.  A plan will be announced at the April meeting. 

The Gene Ramsey Memorial Reconstruction Fund is over halfway to its goal of $9,000.  Contributions from members are a great way to honor Gene, who did so much for many years for AAAP and the Observatory.  We are seeking ideas on ways to honor Gene with an appropriate gesture, for example a mounted plaque on the new columns when the reconstruction is completed.  Please send me an e-mail with your idea or comment during the upcoming meeting.  Donations can be made directly and securely on the AAAP website (the yellow “Donate” button on the right side of the home page), or checks can be mailed to:  Treasurer, Amateur Astronomers Assoc. of Princeton, Inc., PO Box 2017, Princeton, NJ 08543.  For larger amounts a check is helpful because the PayPal fee is significant.  Contributions are tax-deductible.  Please consider corporate matching if it’s an option for you.

You can help reduce light pollution – here’s some ideas.  I have the honor to give a presentation on lighting issues in astronomy and wildlife in observation of Earth Day during Hopewell Valley Green Week this month, through the Friends of Hopewell Valley Open Space (FoHVOS).  It would be great to have a few AAAP members on this Zoom April 21 at 8:30pm;  register for it here:   http://events.r20.constantcontact.com/register/event?oeidk=a07ehp7kfhz5b6d31ad&llr=ojvikdxab.  I also wrote an article published in MercerMe on the topic.  https://mercerme.com/of-moths-birds-and-the-milky-way-the-importance-of-reducing-artificial-lighting-at-night/ 

Another way to help is to ensure that minimal lighting is part of the emerging park planning for the Moores Station Quarry property in Hopewell Township, adjacent to Baldpate Mountain Park.  The Mercer County Park Commission is undertaking a public planning effort to develop a park master plan for the site.  You can help avoid a future prospect of more lighting interfering with our Observatory at Washington Crossing only a mile away from the Quarry.  To help, review the county plans and take the survey on their website and add your comment to request minimal outdoor lighting in the plan.  https://www.mercercountyparks.org/#!/about/moores-station-quarry-park-plan

Revolution in imaging technology – CMOS sensors and amateur astronomy.  The past decade has seen remarkable advances in semiconductor technology which are impacting astronomy in big ways.  The type of sensor used for astrovideo and long exposure astrophotography is shifting rapidly throughout the world of amateur astronomy.  The major companies making sensors, such as Sony and ON Semiconductor, have announced plans to discontinue production of CCD sensors entirely in favor of CMOS technology.  CMOS stands for complementary metal oxide semiconductor, not a very helpful name for the end user.  Of course, amateur astronomers have used DSLRs (with CMOS) for years, but the big push now is development of cooled and optimized astronomy-dedicated cameras using these sensors. The CMOS sensor converts photons to electrons for digital processing, where each pixel amplifies its own signal making the readout lighting quick compared to the slower readout from a CCD sensor.  This enables the near-real time performance of CMOS in the setting of EAA, or what I like to call astrovideo sessions.  Moreover, the read noise (electronic noise from the transfer of signal out of the sensor) is markedly lower than similar sized CCD sensors, critical to revealing faint detail in astronomical targets.  Importantly, cost is substantially lower for CMOS devices relative to CCDs.  With the advent of back-side illuminated (BSI) CMOS chips, quantum efficiency (QE) in some of the newer sensors now exceeds 90%.  For example the club’s ZWO ASI-294MC Pro color camera (used with the Celstron-14 in recent astrovideo live sessions) has a BSI chip with QE ~75%, very high for a color sensor.  Recently, ZWO and QSI astro-camera companies described new astro-cameras based on APS-C sized and full frame monochrome and color sensors using the newest generation Sony BSI CMOS chips.  These developments are game-changers in the field for amateur astronomy, as few sensors of this size were available in the CCD world (and cost a fortune).  Similarly, some of the new cameras with smaller chips along with very small pixel sizes are perfectly suited for shorter focal length refractor telescopes which many amateur astronomers own.  It’s fair to say that there is a revolution in imaging technologies underway, and amateur astronomy is right on top of the wave.

The open star cluster, Messier 67 in the constellation Cancer.  Image taken with a ZWO ASI-071MC color CMOS camera and 12.5” reflector telescope on March 29 from Titusville NJ.  At 3.2 billion years, M67 is thought to be the oldest of all the Messier clusters.  Note the reddish stars – the cluster is so old that its originally bluer stars have passed beyond that stage of development