On the night of Jan 08/09, 2021, under fair (and cold) conditions, I acquired images of
Once again, Ross 248 shows the same "jump" in RA as the UT Dec 11 measurements, but all other values are about as expected. Hmmm.
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:
Notes from the night:
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:
The dark current was normal this evening:
The sky value increased due to light clouds, then decreased again as they left (briefly).
The number of objects detected.
The FWHM was nice and small.
Here are the positions I've measured so far. Note the clear motion to the south-east (lower-left).
I wondered if there might be a reason in the sky for the "jump" in RA in 3 of the 4 most recent nights. I checked the POSS images, and there are two stars slightly to the West of Ross 248 -- which is the direction of the "jump". One is an 18th mag star about 7 arcsec to the West, the other a 16th mag star about 12 arcsec to the West. I believe that my centroiding algorithms should not include much, if any, of the light from those stars, but it would go in the right direction ....
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 clearly moving in the positive RA and Dec directions, as we would expect from its known (large) proper motion.
These measurements do NOT show the same "jump" in RA as those of Ross 248; and, thank goodness, the previous measurement in Dec (dark blue symbols) may just turn out to be an isolated outlier (I hope).
Last modified 1/9/2021 by MWR.