AAVSO Photometry CHOICE Courses

At present there are three AAVSO CHOICE Photometry courses, two for monochrome CCD/CMOS cameras and one for DSLR cameras. These courses require daily commitments of time from each student to complete successfully. This includes time taking and processing images as well as participation in discussion questions on the forum. Students will be asked to share their results with the instructor and with other students. An “open book” final test is required from each student.

CCD Photometry Equipment Requirements

The purpose of the CCD Photometry – Part I (CCD 1) and CCD Photometry Part II (CCD 2) CHOICE courses is to instruct students in basic photometry so that they can carry out research on light variation of stars and star systems and submit their observations to AAVSO, other organizations, or use the results for their own research activities.

DSLR’s and one-shot-color CCD/CMOS cameras are not suitable for CCD1 and CCD2. If you plan to use a monochrome CMOS camera, you should be experienced with making your own decisions on camera gain, offset, and stacking settings.

The CCD1 instructor for Fall 2021 has photometry experience with the CMOS ASI183mm but might not be able to help you with other brands or models of cameras. The instructors will provide images for students with cameras which are not supported by the course and for users of CMOS cameras who need more experience with camera settings.

Students contemplating photometric observations should purchase at least two photometric filters. Johnson V and Johnson B are recommended. Students transitioning from astrophotography who are
not sure that they wish to pursue photometry but want to enroll to see if photometry interests them may use their RGB filters for both CCD 1 and CCD 2. The magnitude measurements may not be as accurate, but you can learn all the same lessons and techniques using RGB filters. The transformation of Green (TG) measurements to V usually gives good results.

When purchasing Johnson-Cousins photometric filters be sure that the transmission curves for your new filters resemble those shown on page 22 of the AAVSO Guide to CCD Photometry. Also, review the AAVSO forums discussions on picking photometric filters.

Students in CCD 1 and CCD 2 are assumed to have suitable software and know how to use it for such activities as taking, manipulating, and analyzing images. For photometric analysis the courses actively support the use of AAVSO’s VPhot tool. Before enrolling please consult the AAVSO Guide to CCD Photometry, page 22, for recommended software.

(Addenda to the software list: AIP4win is now available as freeware. Also, consider the newer software package AstroimageJ.)