Report on the 41st Symposium on Telescope Science

2023 February 7

David Boyd

The 41st annual Symposium on Telescope Science, organised by the Society for Astronomical Sciences (SAS), took place in Ontario, California on 2022 June 2–4. After two years of holding the event virtually, via Zoom, this was the first time many of the participants had met each other in person for three years. Attendance was slightly lower than in previous years, with 60 booked to attend in person and 34 joining via Zoom. My attendance was generously supported financially through the BAA Ridley Grant scheme.

As is normal for these events, the first day consisted of workshops. This year the theme of the morning session was ‘Projects I wish someone would do’. Tom Maccarone from Texas Tech University invited participation in a long-term project to observe the black-hole binary Cygnus X-1. Brian Warner and Alan Harris pointed out that in spite of the current all-sky surveys, there was still much work to be done by amateurs in observing and measuring asteroids. They encouraged the search for binary asteroids and observations at low phase angle.

Arne Henden, a past Director of the American Association of Variable Star Observers (AAVSO), suggested trying to record the light curve of the Crab pulsar using a CMOS camera. He also invited observations of Polaris, which he said could reveal more information about the subtle changes which have been taking place in the star’s behaviour over recent years. Given its brightness, he suggested these observations could be made in daylight. He asked for volunteers to help with processing data from the AAVSO Photometric All-Sky Survey (APASS) and operating the ongoing APASS2 project, which extends the bright star limit.

In the final presentation of the morning session, I encouraged amateur spectroscopists to use concurrent photometry to calibrate their spectra in absolute flux to make them more useful to, and potentially increase their use by, professional researchers. I gave examples of how this could reveal a more complete picture of the behaviour of some types of objects and described in detail how to go about this. In the afternoon session, Wayne Green reviewed the use of CCD and CMOS cameras in scientifically motivated amateur astronomy and generated a lively discussion on ways to exploit the operational characteristics of new CMOS cameras.

The following two days of the Symposium were devoted to talks covering many aspects of small-telescope science. Themes covered in talks delivered either in person or online included using practical observing projects within secondary-school science education, making use of data from space missions such as Gaia, Kepler and TESS in amateur projects; developing new spectroscope designs, ongoing monitoring of the long-term behaviour of specific variable stars, planetary observation using narrow-band filters, projects to monitor seeing conditions and light pollution, and development of CubeSats by small teams for Earth observation and astronomy. Several of these activities included active collaboration between the amateur and professional communities.

The following short summaries describe a selection of the papers I found particularly interesting.

There were four talks by a team with members in the US and the UK, including myself, who are working with professional support to study the behaviour of flare stars using a combination of photometry and spectroscopy. The group developed through regular online meetings during the pandemic and are now producing data which augment professional studies of these objects.

A collaborative group of amateur astronomers with professional backgrounds in electronics, optics, mechanical engineering and computing, including UK member Tony Rodda, has been designing a new generation of automated spectroscopes which overcome many of the recognised problems with the current generation of commercial devices in use within the amateur community. It will be interesting to see if this work leads to a commercially available product in the future.

There was a talk by John Menke, a long-term developer of novel amateur spectroscopy projects, in which he described his double-grating spectroscope. This uses a dichroic filter and two gratings to record the red and blue parts of the spectrum separately and simultaneously. He uses this to study AZ Cas, an eclipsing binary with red and blue giant components and an orbital period of 9.3 years. This is a good example of the long-term dedication of some amateurs.

Three papers by students of the Stanford Online High School described ambitious observing projects, some of which produced good results while others were less successful. Success, however, was not the most important criterion for these projects. They provided a valuable learning experience and the knowledge that science does not always produce the results you expect. Some of these students were able to use the 60-inch Hooker telescope on Mount Wilson for their project, which must have been an amazing experience.

Tom Polakis described the use of Differential Image Motion Monitors to measure seeing at two Lowell Observatory sites. This employed two C14 Schmidt–Cassegrain telescopes with masks containing two offset apertures, one with a low-dispersion prism which moved the image of a star horizontally on the detector with respect to the image of the star through the other aperture. Wind or mount instability caused the images of both stars to move together, and so could be eliminated, while seeing changes made the two images move independently. Seeing was measured from the variance in the relative positions of the two images during video capture. By varying the shutter speed, the frequency of seeing variations could also be measured. This provided quantitative data on seeing at various locations around the Anderson Mesa observing site, to assist in locating a new telescope.

Chris Baddiley from the UK presented a comprehensive paper on his experience of measuring light pollution over many years, in particular at the Malvern Hills AONB. He has developed an analytical model of light from luminaires reflected and scattered from various surfaces and performed a series of measurements of night-sky brightness.

Epsilon Aurigae was the subject of an intensive pro-am observing campaign during its eclipse in 2009–2011, including contributions by BAA members. John Martin, from the University of Illinois, presented results of continuing spectroscopic monitoring of the complex H-alpha feature over the subsequent 10 years. These have revealed continuing changes in this feature, which emphasises the need to keep observing this enigmatic object.

Narrow-band imaging of planetary atmospheres is an area of increasing interest to amateurs. Steven Hill presented a paper on his observations of the Jovian optical ammonia band at 645nm during 2020 and 2021. Although less prominent than methane absorption in Jupiter’s atmosphere, he argued that ammonia-absorption imaging can provide additional data to inform atmospheric modelling. In the paper, he also provides advice on best practice in performing these measurements.

The proceedings of this year’s Symposium are available on the SAS website here.