[vsnet-alert 23918] Re: PNV J17561375-2942546: possible nova (11.5 mag) in Sagittarius

[Brian Skiff]

Lacking proper Cousins I photometry, you can do pretty well by simply using Sloan i and z magnitudes:  Ic = (i+z)/2.   In this part of the sky the Pan-STARRS Sloan data are probably preferable to SkyMapper simply because of the larger image-scale and psf-fitting (they used aperture-photometry for the first version of SkyMapper).  The bright limit of Pan-STARRS, however, is about mag 13.5 in any band.  For brighter stars, use SkyMapper if not too crowded.  These catalogues are VizieR items II/349 (Pan-STARRS) and II/358 (SkyMapper).  The astrometry in Pan-STARSS, by the way, is at least as good as UCAC4, so perhaps for most applications you could replace use of UCAC4 altogether.


\Brian


> On Feb 1, 2020, at 3:50 AM, Josch Hambsch <hambsch at telenet.be> wrote:
> 
> I have taken BVI images of this object last night.
> The position is:
> RA 17 56 14.04, DE -29 42 58.2 (J2000.0)
> 
> At JD 2458880.89604 the V magnitude was 11.18 (+/-0.01) mag, B magnitude was 12.42 (+/-0.03). Airmass was 1.8.
> Still need to find I magnitudes for the comp stars as the ones chosen did not have I mags in the UCAC4 database.
> Data will be sent to the AAVSO database.