DSLR photometry using VPHOT possible ?

American Association of Variable Star Observers (AAVSO)
Fri, 06/16/2017 - 01:53

Hi All,

I'm a novice to VPhot.  Just wanted to know if:

1) DSLR photometry is possible using VPhot if I process images using IRIS ?

2) Are images to be plate solved before I upload them for photometry ?

Thanks in advance.

Astronomical Society of South Australia (ASSAU)
DSLR photometry using VPHOT possible ?

Re: 1), I use IRIS to create calibrated, stellar-registered images with color channels separated, saved as FITS files.

Until recently I was only doing photometry via IRIS too, i.e. extracting instrumental magnitudes then using the ensemble approach with spreadsheet created by Mark Blackford and others (originally Citizen Sky).

Re: 2), more recently I've been going on to use AstroImageJ to plate solve the images before upload to VPHOT.

I also wrote a script (on github; happy to share) to update the FITS header before upload. It also adjusts midpoint time etc, useful even for IRIS-only photometry.

I have not transitioned away from the ensemble/spreadsheet approach yet because for one thing I don't yet have a good quality set of transformation coefficents for my wide-field equipment (Canon 1100D). For another, it works quite well. I'm mostly trying to explore the possibility of reducing the amount of time it takes to get through the processing and improve efficiency.

So, my VPHOT DSLR photometry is still in the experimental stage.