On the night of Oct 27/28, 2021, I observed the eclipsing binary star V1004 Cyg for one of our capstone projects. The measurements would largely repeat a section of the light curve we'd already covered, but we would see additional portions of the light curve of the other variable star in the field. I also acquired images of GX And and Ross 248 for the long-term astrometry project.
There were no problems with equipment, and all went well.
I acquired images of the eclipsing binary system V1004 Cyg as part of a capstone project.
The main setup was:
Notes from the night:
The object is located at
RA = 19:50:29.44 Dec = +33:08:32.2 (J2000)
A chart of the field is shown below. The size of the chart is about 31 x 26 arcminutes.
I've marked the location of several comparison stars as well. You can find reference magnitudes for these stars at the AAVSO:
I used the star marked as "C" in the picture above, or "118" in the AAVSO charts, to shift the instrumental magnitudes to the standard scale.
| Label | B | V |
| C | 12.717 | 11.803 |
I took a photo of the finder TV's screen when pointing to this target; this could be a useful reference for the future:
The sky value shows no clouds at all. Nice.
The FWHM graph below shows that my adjustments increased FWHM in B-band, but they were decreasing FWHM in V-band; it turned out okay.
Using aperture photometry with a radius of 10 pixels in B and V filters (binned 2x2, each pixel is 1.24 arcsec, so a radius of 12.4 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.
Sigma-vs-mag plots show that the floor was about 0.008 mag in both bands. The target is the fainter of the two outliers around instrumental mag 4.2; the bright outlier at mag 1.3 is the variable with unknown period.
The change in zeropoint shows again that there were no clouds, just a change due to airmass as the target set in the west.
This is one of the stars that a capstone student may study over the next year in a project involving parallax. Ross 248 is a relatively faint red star surrounded by many other stars of similar brightness, so it's a good candidate for high-precision parallax measurements.
These observations involved:
The object is (currently) near position
RA = 23:41:55.27 Dec = +44:10:06.38 (J2000)
A chart of the field is shown below. The size of the chart is about 41 x 27 arcminutes. The noisy area at right (West) is the shadow of the guider's pickoff mirror.
I've marked the location of several comparison stars.
star UCAC4 B V r ------------------------------------------------------------------------- A UCAC4 671-120730 12.617 10.689 B UCAC4 671-120688 C UCAC4 671-120749 10.987 10.663 P kappa And 4.06 4.14 --------------------------------------------------------------------------
I took a photo of the finder TV's screen when pointing to Ross 248; this could be a useful reference for the future:
Here are the positions I've measured so far. The most recent measurements are at bottom right.
Like Ross 248, GX And is a nearby (binary) star which will be the target of a parallax project in the coming year. One of the two components is bright -- about mag V = 8 -- so one must use short exposures to prevent it from saturating the detector. That may mean that this system isn't as easy to measure as Ross 248 or some others.
The object is currently close to this position:
RA = 00:18:28.4 Dec = +44:01:31 (J2000)
but it does have a very high proper motion.
A chart of the field is shown below. The size of the chart is about 41 x 27 arcminutes. The noisy area at right (West) is the shadow of the guider's pickoff mirror.
The two components of the GX And binary sit inside the box. I've marked the location of several comparison stars as well.
star UCAC4 B V r ----------------------------------------------------------- A 671-001473 9.939 9.790 B 670-001639 9.413 8.472 C 671-001509 12.712 11.421 11.001 -----------------------------------------------------------
I took a photo of the finder TV's screen when pointing to GX And; this could be a useful reference for the future:
Using the same techniques as described for earlier nights, I matched detected stellar positions to the Gaia DR2 catalog.
The target is moving to the upper-right with time, and clearly shows the back-and-forth motion due to parallax.
Last modified 11/02/2021 by MWR.