PSN J09554214+6940260 in M82 - mag V 11.7

[Olivier GARDE]

Cool Olivier. You spectrum is in good agreament with Christian ALPY spectrum, except for wave lenght beloww 5000A. Who said that eShell was for bright target ... Well, a LISA ou ALPY will perform better, but it's still possible with the eShel.
Regards
Thierry Lemoult

Yes Thierry, I don't have a lot of flux in the blue part of the spectrum even with 4H30 exposure.

I will also try as you did with a relatively faint NP, which should perhaps be easier because there is the [OIII] lines in emission.

[Christian Buil]

Spectrum the 02/03/2014 (9x600 sec. on C11 tel. + Alpy 600):



Fast evolution:



Christian

[Paolo Berardi]

Excellent spectra despite the lower brightness! The eShel spectrum by Olivier is incredible! Christian 600 l/mm spectrum, eShel and mine with 1200 l/mm show two weak absorption line to the left of Na I D lines. I wonder if they could be diffuse interstellar bands at 5780.5 and 5797.1 mentioned in ATel 5859 (http://www.astronomerstelegram.org/?read=5859).

Christian, it seems to me that a similar evolution (a large profile variation around 5500A) is also shown by SN2011fe (type Ia in M101) in the same period (about a month after maximum).

Current SN light curve RVB by AAVSO (http://www.aavso.org/lcg):



Paolo

[Filipe Dias]

I have these two observations taken with SA100.. These are the two first spectra I ever took with SA100.. So I expect them to be wrong in some aspect... How "wrong" do they look?

They represent SN2014j, subtracted by the just-above&below sky background that includes M82 spectrum.
No attention to instrumental response. Callibration using 0-order + O2 absorption (on the second bright star from M82 - TYC 4383-1099-1)

Pink: 20140226 20:55UT SA100, Atik314L+, 8,3" Newt F/3.9, 22 x 3min, disp 12,57 ang/pix
Blue: 20140303 21:10UT SA100, Atik314L+, 11" Cass F/6.7, 26 x 3min, disp 15,96 ang/pix

Pink - Subtracted the sky in Iris before subtracting again (M82 spectrum) in Vspec, so this is likely a cause for the noisy spectrum.

[Robin Leadbeater]

Hi Fil,

That looks like a great start for your first Star Analyser spectrum (but of course you are not a beginner in spectroscopy ) It is indeed very easy to add extra noise when doing the background subtraction. The key is to use as wide a region as possible to give a good average but still make the background representative, something which is difficult to do in this case of course.

The usual way to wavelength calibrate is to use the Balmer lines in reference A star which gives better defined lines and allows a non linear calibration. This star can also be used for instrument response correction. I normally start a Star Analyser observing session with the reference star and use it to adjust the focus before moving on the fainter targets.

Another question. did you guide your exposures or can you take 3min exposures unguided?

Cheers
Robin

[Filipe Dias]

Hi Robin,
They are unguided, yes.. the star was drifting about 1 stellar diameter (3.6") per 3 or 4 images (~10 min).. But I did spend around 45 min drift-aligning the mount (not in an observatory yet). Having this light drift causes hotpixels to fall out of place in consecutive images, but they were all cleaned-out with the dark! (hotpixels in registered images are a nice way to measure drift, by the way)
The stars, however, are longer in roughly the N-S direction.. I suspect there is backlash/play in DEC, and some tiny wobble in that direction (light wind), or most likely wobble in the up-down direction of the entire mount due to my "tripod adapter" made of wood that was bent by humidity/moisture providing precarious attachment..
The mount used for the images is a very pleasing Takahashi NJP Its periodic error is not easy to notice at the declination of M82 (+70º), and far less in 3 min exposures... But it is not advisable to push much longer than this unguided...
But the star with the C11 + reducer is a bit largish.. Maybe I placed the camera too far away from the reducer... The SA100 might have been too close to the camera, so all that may have smoothed my spectrum.. The dispersion direction is also very close to the N-S wobble and so the star is longer in that direction as well.. So all that is conspiring against the resolution of the spectrum

[Olivier GARDE]

The supernova is too low in magnitude to be made with Eshel spectrograph, but I could take an image of the Sn which shows that it is less bright.

[Olivier GARDE]

Sn 2014 J taken with a LISA and C14 last night.

Here's a poster

[Christian Buil]

C'est vraiment très bon, et quel magnifique observatoire !

Christian

[Paolo Berardi]

Incredible... spectrum and observatory!
Congratulation Olivier! Waiting for your deep space object spectra!

Soon we will have another great observatory... but in Idaho!

Yesterday I've also observed this SN, I have to reduce spectra.

Paolo