V420 Aur (HD 34921) observing campaign

American Association of Variable Star Observers (AAVSO)
Mon, 10/03/2016 - 23:20

AAVSO Alert Notice 554 announces an observing campaign on the bright (V=7.15-7.35) Be star V420 Aur (HD 34921), which is in a high-mass X-ray binary system (HMXB) with a neutron star. The notice gives details of the optical support needed (beginning immediately)  for high-resolution spectroscopy scheduled October 7-17.

Many thanks for your observations, and good observing!

Elizabeth Waagen, AAVSO HQ

Royal Astronomical Society of Canada (RASC)
V420 Aur, not V420 Oph

The alert Notice reads:
Charts with a comparison star sequence for V420 Oph may be created
using the AAVSO Variable Star Plotter (VSP, https://www.aavso.org/vsp).

Please submit observations to the AAVSO International Database
using the name V420 OPH.

Some observers might be confused, it should be V420 Aur



American Association of Variable Star Observers (AAVSO)
Name correction in Alert Notice 555

In Alert Notice 554 on V420 Aur, I inadvertantly referred to the star as V420 Oph for creating charts and submitting observations. AAVSO Alert Notice 555 corrects the information. To create charts, use the name V420 Aur and when reporting observations please use V420 AUR. My apologies for the mix-up.

Good observing,


British Astronomical Association, Variable Star Section (BAA-VSS)
spectra of HD34921

I see the notice mentions that there have been no spectra taken of this star for over a decade. It might be of interest that there are several spectra of this star in the Pro-Am BeSS database,


The last observation was made at H alpha on 2015-12-13 at  and a echelle spectrum with partial coverage was taken 2014-12-04 at R =50000 


No comps in VSP

Perhaps this is not the correct way to raise this issue, so please accept my apologies in advance. I mention it here because the alert notice specifically requests, DSLR observations, inter alia.

When I attempt to plot charts and check the DSLR box, I almost never get any comparison stars. I am wondering, why is that? If I leave the box unchecked, of course comps come up and the photometry table is populated. That is what I do for my DSLR photometry. But I am wondering if I am doing something wrong, or whether instead the software in VSP simply either isn't working or has not been implemented.

PS:  Chart x16684IE (3 degree field) produces a number of good quality comp stars as listed in the accompanying photometry table.  Repeat the exercise with the DSLR box checked, and there are none.