SN2012aw in Messier 95

[Christian Buil]

Spectra of SN2012aw taken the 24.8 April (C11 + LISA):



Note large evolution of the spectrum

Christian Buil

[Paolo Berardi]

Many changes compared to early spectra! This is my first SN spectrum (unfortunately I've been very busy during last period), obtained with Lhires III/150, 35 microns slit and C9.25 from L'Aquila (sub urban site). Response calibration with Denebola (beta Leo):




DAT profile:
http://quasar.teoth.it/html/varie/SN2012aw_20120425.dat


During operations... Lodestar on slit for target position check. Guiding on field star through guide scope and SXV-AG:



SN in slit field with Lodestar, 4 and 6 seconds exposure time:


Ciao!
Paolo

[Francois Teyssier]

Excellent Paolo,
I see on AAVSO site that V magnitude of SN 2012aw is 13.5
It looks you have a good autoguiding with AstroArt. Could you describe it ?
Yous says you've guided in a star field. Is the visualisation window of Astroart shows either the guiding star anf the objrect on the slit (With MaximDL, the maximum size of guiding window is 128x128, so often, we cant see the object.
All the best
François Teyssier

[Paolo Berardi]

Thank you François! Sorry for the lack of information that I gave you earlier. For guiding I used a simple system with two cameras. Also I have noticed that in the sky away from the milky way is difficult to find a valid guide star in the spectroscope slit view field...

Faint target as this SN disappear when they are centered in the 35 micron slit (with a few seconds of exposure), so Lodestar camera is mounted on Lhires "slit view" for checking purpose. Guiding is done on a brighter star by a second camera (SXV autoguider) through a guide scope (90 mm Maksutov-Cassegrain) mounted in parallel to main scope. I start two Astroart sessions, one for Lodestar only (left window in screenshot, 2 sec continue refreshing that does not interfere with main camera operations), the other for main camera and SXV autoguider.

During exposures I check slit view frames for any off-slit error. Typically I have the need to recenter the target every 15-20 minutes (due to differential flexures). I do it quickly, without suspending integration, with some micrometric mount adjustment followed by a guide star resync in Astroart.

I know IRIS/Audela guide on-slit capability but so far I haven't tried these functions and I don't know if target brightness (13+) is sufficient to work correctly. If you have experience with these capabilities and a Lodestar, please tell me about. Anyway, I use a G11 mount type and I wouldn't use guide exposure times too long because there are some little, but fast, tracking errors. I get best results with exposure less than 0.3-0.4 seconds.

Astroart can open very large guiding view by selection box (I have to check the limit). This is useful if there is a valid guide star in the field of slit with similar target brightness, otherwise (eg. guide star much more bright than target), Astroart level autostretching is able to hide completely the target.

Cheers,
Paolo

[Christian Buil]

New spectrum for the date May 2.8 (LISA + C11) :



Christian B

[Paolo Berardi]

May 10.966 SN spectrum (LHIRES III 150 + C9.25):



DAT profile:
http://quasar.teoth.it/html/varie/SN2012aw_20120510.dat

Ciao!
Paolo