NOVA CYGNI 2008 #2 (V2491 Cygni)

Nova Cygni 2008 #2 discovered by Koichi Nishiyama (Kurume, Fukuoka-ken, Japan) and Fujio Kabashima (Miyaki-cho, Saga-ken, Japan) of a possible nova (mag 7.7) on two 20-s unfiltered CCD frames (limiting mag about 12.5) taken on Apr. 10.728 UT using a 105-mm-f.l. f/5.6 camera lens (see IAUC 8934). At the date of discovery the magnitude is near V=7.5. Position R.A. = 19h43m01s.96, Decl. = +32°19'13".8 (equinox 2000.0).

April 13.063 UT, 2008 observation (V=8.5, source AAVSO)
Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: 0.2 meter telescope (Takahashi CN-212) + Echelle spectrograph (R=8000) - see technical details here + fiber link + Audine KAF0402ME CCD camera - Exposure 14 x 300 s.
Nearly the first light of the Echelle spectrograph, in test phase. Spectrograph used in a degraded resolution R=5000 mode (the nominal 85 mm f/1.8 camera lens is replaced by a 50 mm f/1.2 lens).

Echellogram of nova Cyg 2008 #2 the April 13.06, 2008.
The image shows orders from 31 to 51 captured on a 768x512 pixels CCD camera (9 microns pixel size). Red is towards the top,
blue is towards the bottom (from order to order). Wavelength increases to the right (within an order).
The H-alpha line is the very large emission feature at the top of the image (covered by the orders #33 et #34).
 

Bin of the échelle order #33 and #34. The instrumental response is corrected.
The measured H-alpha FWHM is about 109 angstroms (5000 km/s). Equivalent Width of about 800 angstroms (80 nm).
The spectrum can be donwloaded here 20080413_063.DAT
 

Acquisition session of the object. Right, the guiding section: The cross mark the position of nova Cygni 2008 #2 (at V=8.5) and indicate
precisely the entrance of the optical fiber. Left, raw CCD image of the nova spectrum (5 minutes exposure - 13/04/1008).

April 19.153 UT, 2008 observation (V=9.85, source AAVSO)
Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: 0.2 meter telescope (Takahashi CN-212) + Echelle spectrograph (R=8000) - see technical details here + fiber link + Audine KAF0402ME CCD camera - Exposure 8 x 300 s.
Nearly the first light of the Echelle spectrograph, in test phase. Spectrograph used in a degraded resolution R=5000 mode (the nominal 85 mm f/1.8 camera lens is replaced by a 50 mm f/1.2 lens).

The field of V2491 Cyg the 19.1/04/2008.
Image taken with the guiding camera (Watek 120N).

Bin of the echelle order #33 and #34. The instrumental response is corrected.
The spectrum can be donwloaded here 20080419_153.DAT
 

 
The echellogram for the date April 19.15, 2008.
The nova is now a faint object (magnitude is near 10) for the setup (0.2 m telescope) and exposure time (45 min).

The setup used for low resolution spectra. Left, at the entrance of the fiber link: a 0.2 m telescope.
At the output of the fiber link: the compact LISA spectrograph
(note the Canon 85 mm f/1.8 camera lens, and at the top, an Audine CCD camera.

April 23.053 UT, 2008 observation (V=9.9, source AAVSO)
Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: 0.2 meter telescope (Takahashi CN-212) + LISA spectrograph (R=1000) - see technical details here + fiber link + Audine KAF1602ME CCD camera - Exposure 9 x 300 s.

The spectrum can be donwloaded here 20080423_053.DAT

April 26.023 UT, 2008 observation (V=9.6, source AAVSO)
Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: 0.2 meter telescope (Takahashi CN-212) + LISA spectrograph (R=1000) - see technical details here + fiber link + Audine KAF1602ME CCD camera - Exposure 8 x 300 s.

The spectrum can be donwloaded here 20080426_023.DAT

 Time evolution