Skip to main content

DW UMa comps

2 posts / 0 new
Last post
marlin's picture
DW UMa comps

I have 84 images of DW UMa but VPhot shows only one comp star.  VPhot requires both comp and check.  Can you add a star to the mix so I can do a time series?

Marlin Costello

MZK's picture
DW UMa Comps


There are several AAVSO comp stars present in a 30' FOV of DW UMa. In VPhot, open one of your DW UMa images. Under catalogs, click add AAVSO Comp stars. The comp stars will be displayed on your image. Select as many as you want (single  comp or ensemble). Highlight one of the comps and change it to a check star.

If you have such a small FOV that only one AAVSO comp star exists, try to load simbad data and see if a star appears near the target. Use it as the check.

If not, select any other star in your FOV and estimate its magnitude by SNR. Input an estimated magnitude for the star and VPhot will use this as the check. Run your time series. Obviously, the magnitude of this check star will not be accurate but you can run the time series.

HTH, Ken (MZK)

Log in to post comments
AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484