On the night of Dec 18/19, 2020, under fair conditions, I acquired images of
As you can read elsewhere, Jupiter and Saturn will pass very close to each other in our sky on Dec 21, 2020. It is, unfortunately, very likely going to be cloudy in Rochester then -- but it was clear tonight! So, even though they aren't as close as they will be eventually, I decided to take a look.
At around 5:10 PM, the sky was still pretty bright. I needed to start observing the pair before it really grew dark because they were already low in the sky. In fact, the two were only about 16 degrees above the horizon when I started to take a short video, using a Sony NeX-6 camera mounted at Cass focus on the 12-inch telescope. Click on the picture below to see a short clip of video.
At this time, I could just barely fit both planets into the same field of view of a single eyepiece. It was quite a thrill to see them both in a single view! The separation at this time was about 20 arcminutes; they will approach to within only 6 arcminutes on Dec 21.
Here, maybe this image will make the point more clearly. It is a composite of two photographs, taken a few minutes apart. The Moon was some 20-25 degrees away from the planets, but it provides a nice indication of the scale.
This bright nova was discovered on Nov 25, 2020. One can find discussions of its properties and pointers to additional information at
It's quite bright, sitting at around V = 9.8 at the current time.
These measurements involved
Notes from the night:
The object is located at
RA = 04:29:18.85 Dec = +43:54:23.0 (J2000)
A chart of the field is shown below. The size of the chart is about 34 x 27 arcminutes.
I've marked the location of several comparison stars as well.
star AAVSO B V r ----------------------------------------------------------- A 000-BNS-437 12.456 11.867 B 000-BNS-438 13.169 12.458 C 000-BNS-439 13.383 12.680 -----------------------------------------------------------
I took a photo of the finder TV's screen when pointing to Nova Per 2020; this could be a useful reference for the future:
The sky value shows mostly clear skies, but a couple of brief, small incursions by cirrus, and then a bigger invasion near the end.
I used an aperture of 7 pix = 8.7 arcsec for photometry in V-band.
Using aperture photometry with a radius of 7 pixels in V-band (binned 2x2, each pixel is 1.25 arcsec, so a radius of 8.7 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.
Sigma-vs-mag plots in V-band show that the floor was about 0.005 mag with 10-second exposures.
The image zeropoint variations echo the sky measurements, due to clouds.
Here are light curves of the nova and the field stars in V-band. The nova rises by about 0.10 mag, then falls by 0.05 mag, over the 2.6-hour observing run.
I have submitted measurements in V-band to the AAVSO.
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 sky values:
The number of objects detected.
The FWHM.
Here are the positions I've measured so far. Tonight's measurements include a Dec value which is far (150 mas) from the expected position. I'm stumped.
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.
Like Ross248, GX And shows a "jump" of about +150 mas in its Dec position tonight. Why should both show the same change? Is it just coincidence? Sigh.
Last modified 12/19/2020 by MWR.