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I suspect the M2 classification may have come from the colour index which would match an M star without reddening but the lack of molecular bands in the spectrum immediately shows we are dealing with a hotter star here (significantly hotter than Betelgeuse)
Cheers
RobinHere is a spectrum tonight (R=1000 using an ALPY 600 with a narrower than usual 10um slit)
https://britastro.org/specdb/data_graph.php?obs_id=13110
It is very red but clearly heavily reddened by interstellar or circumstellar dustVSX suggests a very wide range of spectrum classifications ranging from G to M2 but Keenan suggests K2i in his 1989 catalogue.
https://articles.adsabs.harvard.edu/pdf/1989ApJS…71..245K
Using the B,V brightness values in SIMBAD, this would imply for a K2i star an E(B-V) = 0.99. Dereddening my spectrum by this amount indeed gives a good match to the Pickles standard for K2i both in terms of the continuum shape and more importantly in the spectral line details (My spectrum is a slightly higher resolution which would explain the higher apparent intensity of the lines in my spectrum)
https://britastro.org/specdb/view_image.php?obs_id=13110Cheers
Robin
EDIT- trying to get the link working.. and failing đ cut and paste it if you need toSome (PEP) photometry in the IR might be interesting. Betelgeuse hardly faded at all in H and J. There is no history for RW Cep in those bands in the AAVSO database though. Does anyone in the BAA have this capability ?
Where does manipulation start though ? For example I would venture to suggest almost every deep sky, comet and planetary image in the gallery has had undocumented processing which affects the scientific value (non linear stretch, sharpening, noise reduction star elimination etc etc). As a science based organisation though contributors should welcome challenge and be able to supply the raw data if required. (With the new website there doesn’t appear to be any simple way to make contact with other members any more though)
Cheers
RobinSo, if youâre trying to fix a broken link, you can generally find the page youâre looking for by changing the broken link into the canonical form and seeing where it redirects to in the new site.
Thanks! Link now points directly at the destination
Cheers
RobinIt has now been imaged by HST and resolved into four lensed components
https://www.wis-tns.org/sites/default/files/astronotes_files/1052/note_color_wide.jpg
from
https://www.wis-tns.org/astronotes/astronote/2022-196Cheers
RobinThis is also my experience. I don’t think these satellite maps are showing the true picture. They are measuring the light escaping into space. (If all the light did that we would have dark skies!) What we need to know is the light which is scattered back which depends on the wavelength and the factors Gianni mentioned. A shift in the spectrum of the light pollution from a predominantly orange to blue at the same light intensity would increase the scattering reducing what the satellite sees but making the skies brighter when viewed from the ground.
Also some LED lights which look like they are full cut off are just flat LED panels with a very wide pattern and no attempt to contain the beam. I have a neighbour a couple of hundred metres away with a very bright one of these. It is directed almost straight down so should be ok but it still overspills into my garden.
Robin
A comparison of the spectrum this maximum with that by Miguel Rodriguez at a more typical maximum is in the latest BAA VSSC
https://britastro.org/vss/VSSC193.pdf
page 16It has now faded to visual magnitude ~7, a brightness more like that typically seen at maximum. The temperature from the TiO bands in the spectrum spectrum has dropped to that more typically seen at maximum, though the intensity of the Balmer emission remains high. Attached is a comparison between my most recent spectrum and that of Miguel Rodriguez taken at the 2020 maximum.
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Attachments:
Finally caught it tonight
40×20 sec clearAttachments:
The ZTF cutouts on the alerce site are useful. There is a faint something (the parent galaxy ?) at the coordinates in the template but this is clearly brighter with the SN (about the same brightness as two other stars in the same string on 25th)
(The clouds rolled in here as dusk fell)
Robin
Attachments:
Align and stack programs like Siril for example
https://siril.org/
can output a series of fits images as avi which can then be converted to animated gifs using various on line toolsCheers
RobinSince the point spread function of each of these stars would be expected to be similar, is it possible to use some kind of psf fitting technique to separate the flux from each component instead of aperture photometry ?
They are obviously having fun combing these images. Here they have found what is left of SN 2013ej in M74
https://www.wis-tns.org/astronotes/astronote/2022-147
which reached mag 12 back in August 2013 seen here in Damian Peach’s image.
http://www.damianpeach.com/deepsky/m74sne_2013_08_05dp.jpgNow past maximum. My two low resolution spectra bracketing the maximum here
https://britastro.org/observations/observation.php?id=20220718_154759_9e171ab7b4e26e1f
Cheers
RobinI see it has already started doing the more mundane stuff. A possible supernova on the Transient Name Server, reported today though from an observation made 2022-06-22
https://www.wis-tns.org/object/2022owj
(I wonder if they embargoed it until after the “first light” images had been published ?)Hi Stan,
There are quite a few images already this year in the members’ gallery
https://britastro.org/observations/?obj1Type=0&obj1txt=Noctilucent+cloud&obj1id=NLC
There is also dedicated section on the forum covering discussions on atmospheric phenomena, though it is pretty quiet
https://britastro.org/forums/forum/atmospheric-phenomena
Cheers
RobinNot sure if I’ve logged this one already but the old link to my profile
https://britastro.org/profile?id=146
which I may have put out there on the internet in the past
now points to
https://britastro.org/forums/reply/profile?id=146
which brings up a random unrelated posting on the forumThere is an early spectrum from the 2SPOT team from their robotic ALPY 600 setup in Chile
https://groups.io/g/spectro-l/message/412
which seems to be evolving fast compared with the description of one taken less than 12 hours later referenced in Atel 15420
https://www.astronomerstelegram.org/?read=15420In times of crisis, I find myself turning to Prof Ned Wright’s tutorials. These FAQ are useful here
What is the redshift ? https://www.astro.ucla.edu/~wright/cosmology_faq.html#z
Can objects move away from us faster than the speed of light? https://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL
Are galaxies really moving away from us or is space just expanding? https://www.astro.ucla.edu/~wright/cosmology_faq.html#MX -
This reply was modified 3 years, 2 months ago by
