On the night of May 03/04, 2015, I observed the cataclysmic variable star CSS 080505:163121+103134. You can read more about this star, which has been detected in only one earlier outburst, at
It showed regular variation during my run, though the signal-to-noise ratio was low.
The main setup was:
Notes from the night
Here's a chart of the field of CSS 080505, which is at
RA = 16:31:21 Dec = +10:31:34 (J2000)
The chart is about 12x12 arcminutes.
Several of the reference stars marked above have photometry listed in the UCAC4. I used star "A" to convert the instrumental magnitudes to the V-band scale (though of course, they are unfiltered measurements)
A = UCAC4 503-064345 V = 11.885
Below is a graph showing the sky brightness as a function of time during the observing run. Note the clouds in the second half of the run.
Below is a graph showing the FWHM as a function of time during the observing run. I refocused once, at 2:24 AM, frame 173.
I used 60-second exposures during this observing run. The target had about 800 peak counts/2 with this exposure time, and the bright stars A and B about 10,000.
Using aperture photometry with a radius of 4 pixels (radius of 5.7 arcsec), I measured the instrumental magnitudes of a number of reference stars and the target. Following the procedures outlined by Kent Honeycutt's article on inhomogeneous ensemble photometry, I used all stars available in each image to define a reference frame, and measured each star against this frame. I used the UCAC4 V-band magnitude of star "A" to convert the ensemble instrumental magnitudes to a reported "V"-band magnitude (but remember, it's a clear filter).
Sigma-vs-mag plot: The target is the outlier at mag 2.8.
The target, shown in green, shows sawtooth variations with an amplitude of about 0.10 mag, with an average magnitude around 14.7.
# Measurements of CSS080505 made at RIT Obs, May 4, 2015 UT, # in fair conditions, # by Michael Richmond, using 12-inch Meade and SBIG ST-9E CCD. # Exposures 60 seconds long, no filter. # Tabulated times are midexposure (FITS header time - half exposure length) # and accurate only to +/- 1 second (??). # 'mag' is a differential magnitude based on ensemble photometry # using a circular aperture of radius 5.7 arcseconds. # which has been shifted so UCAC4 503-064345 has mag=11.885 # which is its V-band mag according to the UCAC4. # # UT_day JD HJD mag uncert May04.11895 2457146.61895 2457146.62356 14.695 0.035 May04.11976 2457146.61976 2457146.62437 14.693 0.035 May04.12056 2457146.62056 2457146.62517 14.693 0.035
Last modified 5/04/2015 by MWR.