2000
June 8: Revisit to Aquila and three novae
- Nova Aql '99[2] and recurrent nova CIAql. Unfortunately Nova Aql'99[1]
appears to have dropped below my threshold of ~m13 for lo-res spectra [disp
= 4nm/pixel] but the starfield recorded here boxed where the spectrum should
be - the faint objects therein are known stars - see below.
1999 Sept 4 -9: VSNet observers report a rapid fade in this nova - my recent spectra [overlaid on spectrum below for Aug 14] show a marked drop in intensity of an emission line at ~570nm which may corrulate with the visual fade. Ha continues as by far the strongest line but does not register on the retina [at low light levels]. Weaker hydrogen lines like Hb etc are still recorded - the latter seems to have merged with an unresolved band [probaby OIII doublet near 500nm].
1999 Aug 9/14: The spectrum below [my first since Nova Cyg '75 = V1500 Cyg; m2.2] covers the whole visible spectrum and into near-IR. It proves very complex with 12 emission lines and some deep absorption lines as listed in the Table below. The hydrogen series in the visible spectrum from Ha to He appears to be recorded.....other lines are to be 'allocated'. Most of the flux appears to be in the Ha emission line so the star could be quite red. Has this been observed or captured on colour film?
The A/pixel column in the Table clearly shows spectral dispersion, although via a grating, is not linear. This is due to geometric distortion via projection of the spectrum onto the CCD. A Rainbow transmission grating was used in the convergent beam of the telescope some 20mm from the CCD. A typical dispersion of ~40A/pixel reflects in the accuracy of estimated wavelengths.
