On the night of Jun 28/29, 2021, under good conditions, I acquired images of Nova Her 2021 = V1674 Her. One can find information about it at
No problems tonight -- just very warm temperatures.
This object was discovered by Seiji Ueda (Kushiro, Hokkaido, Japan) on 2021 June 12.537 UT. It rose quickly, then fell quickly.
The main setup was:
Notes from the night:
The object is located at
RA = 18:57:30.95 Dec = +16:53:39.6 (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. See
I'll use star "E" to shift my instrumental magnitudes to the V-band scale. It has a V-band magnitude (according to AAVSO chart X26675JQ) of 12.221, and (B-V) = 0.608.
The faint star marked "var" shows variations of size roughly +/- 0.3 mag in a roughly sinusoidal pattern over the run. It's perhaps an eclipsing binary. The star has magnitude V ~ 13.5 and position
RA = 18:57:04.13 Dec = +16:46:00.9 (J2000)
= 284.26722 = +16.76692
You can use its entry in the APASS catalog to look it up in Vizier, and to serve as a cross-reference.
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 beautifully smooth and flat curve -- no clouds.
The FWHM graph below shows quite a bit of scatter. I used X aggr settings of 5 at the star, then switched to 3 later on, around one hour into the run. I'm not sure which was better. The typical stellar PSF was trailed East-West significantly - roundness = -0.7 - so I need to run tests to find a better setting.
Using aperture photometry with a radius of 7 pixels in a V filter (binned 2x2, each pixel is 1.24 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 show that the floor was about 0.005 mag with a 60-second exposures. The outlier at instrumental mag = 3.1 is the target. The faint variable is the second-highest outlier around instrumemtal mag = 4.0.
Most of the changes in image-to-image zero-point are due to trailing; I discarded all images with an zeropoint of more than 10.02; there were not many of them, thanks to the improvement in guiding. I ended up keeping 275 out of 350 images.
Here is the light curve of the object and several field stars in the V filter; I've shifted the instrumental magnitudes so that star "E" = 000-BMD-913 on AAVSO chart X26675JQ has the value given by AAVSO as its V-band magnitude. The faint variable star is labelled as "X".
Can we still see any of the variations with period of about 8.4 minutes? Using the Periodogram tool at the NASA Exoplanet Archive, I computed the power spectrum of these measurements. The second-highest peak has a value close to 0.0058 days, which corresponds to 8.4 minutes.
I have submitted these measurements to the AAVSO, CBA, and VSNet.
You can download my measurements below. A copy of the header of the file is shown to explain the format.
# Measurements of Nova_Her_2021 made at RIT Obs, UT 2021 Jun 29, # in good conditions, # by Michael Richmond, # using Meade 12-inch LX200 and ATIK 11000. # Exposures 60 seconds long, V 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 7 pix = 8.8 arcseconds. # which has been shifted so AAVSO 000-BMD-913 has mag=12.221 # which is its V-band magnitude according to AAVSO. # # UT_day JD HJD mag uncert Jun29.08505 2459394.58505 2459394.58951 12.680 0.018 Jun29.08590 2459394.58590 2459394.59036 12.682 0.018
Last modified 6/29/2021 by MWR.