[vsnet-obs 20021] Re: N Sgr 98 not bright

[Taichi Kato <tkato>]

Re: [vsnet-obs 20012] N Sgr 98 not bright

> Recent reports that Nova Sgr 1998 remains bright (mag =3D 12.4) are
> suspect since there is a star of about that magnitude ( I measured V(bb) 
> = 12.3 on 30 Mar 99 ) located 147" to the northeast (P.A. 35 degrees) of
> the nova position.  On the same night I measured the nova to be approximately
> V(bb) = 14.1.
> 
> The notation V(bb) indicates that I used a broad band V filter, namely a
> CCD with a "minus-IR filter".

   The nova looks presently in nebular phase, as judged from the light
curve.  During the nebular phase, nebular emission lines such as
[O III] can be very strong.  Since these lines are more sensitive to
dark-adapted eyes than to CCDs, the difference in magnitudes can be
explainable.  In some previous novae, notably PW Vul and QU Vul, the
difference between visual and photographic V magnitudes amounted up to
1.5 mag during this stage.

Regards,
Taichi Kato

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