On the night of Nov 28/29, 2020, under good conditions, I acquired images of four different targets:
These are my first measurements of Nova Per 2020.
This bright nova was discovered on Nov 25, 2020, so it is just a few days old at this point. One can find discussions of its properties and pointers to additional information at
It's quite bright, reaching into the mag 8 range at latest report.
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 that the sky was clear.
I used an aperture of 9 pix = 11.2 arcsec for photometry in B-band, which was out of focus (the B-filter is not parfocal with V, R, I). For the in-focus V, R, I, I used a 5-pixel = 6.2 arcsec aperture. The chart below shows the FWHM in V.
Using aperture photometry with a radius of 5 pixels in V-band (binned 2x2, each pixel is 1.25 arcsec, so a radius of 6.2 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 0.004 mag with 5-second exposures, and in the B-band, about 0.006 mag in 20-second exposures. The graph below shows the V-band results.
The single low point in the photometric solution is due to one image with a longer exposure time.
Here are light curves of the nova and the field stars in B-band and V-band. The nova rises slightly, by about 0.15 mag over the 6-hour observing run.
I have submitted measurements in B-band and V-band to the AAVSO.
You can find some basic information on this star at the SIMBAD's page for it.
The main setup was:
Notes from the night:
The object is at
RA = 23 11 17.9 Dec = +52 59 59.2 (J2000)
A chart of the field based on pictures tonight is shown below. The size of the chart is about 38 x 26 arcminutes.
The stars "A", "B", and "C" appear in the charts and tables for this field made by the AAVSO. see
In the table below, I've used the AAVSO values for magnitudes in BVI. For R, I've started with the "fitted R" value from Pickles (PASP 122, 1437, 2010) and computed a small correction, based on the differences between AAVSO R and Pickles fitted R for other stars of similar brightness in other fields.
star B V R I -------------------------------------------------------------- A 10.336 10.296 10.082 9.985 B 10.296 9.849 9.492 9.328 C 12.583 10.553 9.592 8.500 F 8.866 8.809 8.722 8.721 --------------------------------------------------------------I used the star labelled A = "102" to shift my measurements to the "R" magnitude scale. It has R = 10.082 according to the Pickles Rf value, shifted by my correction factor.
Here's a picture of the TV with the finder's field of view when pointing at RT And:
The dark current was normal this evening.
The sky value shows that the sky was clear.
The number of objects detected.
I used an aperture of 9 pix = 11.2 arcsec for photometry.
Using aperture photometry with a radius of 9 pixels (binned 2x2, each pixel is 1.25 arcsec, so a radius of 11.2 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 0.004 mag with 13-second exposures. Good!
The single jump in the photometric solution is due to one image during which I slewed the telescope.
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:
The sky value shows no sign of clouds.
The number of objects detected.
The FWHM.
Here are the positions I've measured so far. Note the clear motion to the south-east (lower-left).
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.
I took two sets of images:
In about 35 of the 50 5-second exposures, at least one pixel in GX And was saturated. Sigh. Did it make a difference in the astrometry? The answer tonight was "perhaps, but not a very significant one." The longer exposures provided more reference stars (average of 42) for astrometry than the short ones (average of 32), and higher signal-to-noise for those stars. As a result, the residuals from the photometric solution were lower in the "long" exposures.
The derived position of the target, GX And, was the same within the uncertainties, and those uncertainties were slightly smaller in the "long" exposures.
I think I should use 4-second exposures in the future for GX And.
The target is clearly moving in the positive RA and Dec directions, as we would expect from its known (large) proper motion.
Last modified 11/21/2020 by MWR.