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Robin Leadbeater
ParticipantOn the other hand if you need lead beaten into sheets for your roof then I’m you man 😉
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This reply was modified 10 hours, 13 minutes ago by
Robin Leadbeater.
Robin Leadbeater
ParticipantI very much doubt that anyone here is a kid,
You never know who is eavesdropping though. Google has already indexed this thread
(I see the forum software has attributed the quote to the wrong person for some reason)
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This reply was modified 10 hours, 23 minutes ago by
Robin Leadbeater.
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Robin Leadbeater
ParticipantARGOS ?
Robin Leadbeater
ParticipantI picked up a couple of cheap dumbbells in the Aldi middle isle a good while back. They did nothing for my pecs but two of the weights have been on my EQ6 for over 15 years now. (The hole is oversize but clamping between two standard weight with sticky backed velcro has held them in place.)
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Robin Leadbeater
ParticipantHi Paul,
ZTF show it as of yesterday at 13.6 g, 13.1 r
https://alerce.online/object/ZTF25abbgajqCheers
RobinRobin Leadbeater
ParticipantA comparison of the current spectrum with one in the low state March 2024
https://britastro.org/observations/observation.php?id=20250810_221150_5f858c960a245997Cheers
Robin5 August 2025 at 12:18 pm in reply to: X-SHOOTER spectrum of 3I/ATLAS: Insights into a distant interstellar visitor #630893Robin Leadbeater
ParticipantSo no detectable gas. (The positioning of the label in fig 2 indicating the band where CN should appear is unfortunate. At a casual glance it looks like the hot pixel there is a signal. Given that they took 6 spectra it is surprising they did not remove them)
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This reply was modified 2 weeks, 5 days ago by
Robin Leadbeater.
Robin Leadbeater
ParticipantProper motion confuses the heck out of some of the bots auto reporting transients. They compare the sky with their library image, looking at the differences and once the proper motion moves the star out of the psf of the library image it suddenly triggers a bright transient ! There are quite a few examples in the Transient Name Server
Robin Leadbeater
ParticipantIf you look at the image cutout at SIMBAD
https://simbad.cds.unistra.fr/simbad/sim-basic?Ident=ZZ+PSc&submit=SIMBAD+search
and blink between the DDS and SDSS images you can actually see the position move between the two survey dates. The J2000 position is between the two (Sometimes for high proper motions you even see a double image Red/Blue in the colour DSS images because of the difference in dates)-
This reply was modified 3 weeks, 4 days ago by
Robin Leadbeater.
Robin Leadbeater
ParticipantAn ApJL preprint on ArXiv today presents events for the probable direct imaging of a lower mass companion of Betelgeuse:
There’s an excellent episode from the BBC World Service “Science in Action” programme on this
https://www.bbc.co.uk/programmes/w3ct6yfm“Have we found Betelgeuse’s ‘Betelbuddy?’ An astronomical mystery seems to be solved as the long-predicted stellar companion to the bright star Betelgeuse has been detected by a team of researchers led by Steve Howell of the NASA Ames Research Center using the Gemini North telescope in Hawaii. Steve discusses this breakthrough alongside astronomer Andrea Dupree of the Harvard Smithsonian Center for Astrophysics, who has discussed the predictions of this star on previous Science in Action programmes.”
27 July 2025 at 2:52 pm in reply to: Request for monitoring of X Per (visual, digital and spectroscopic) #630780Robin Leadbeater
ParticipantHere is some further information from Alexander on the spectroscopy side which I have been asked to also distribute to the wider spectroscopy community. It is similar monitoring to that requested by Paul Roche which covered mainly 2018-2021 and was reported on the ARAS and BAA forums
https://www.spectro-aras.com/forum/viewtopic.php?t=2128
https://britastro.org/forums/topic/request-for-monitoring-of-x-per————————————————————————————-
Call for Spectroscopic and Photometric Monitoring of X Persei (4U 0352+309)Observers are invited to join a monitoring campaign on the Be/X‑ray binary X Persei, which is currently in an unusually low X‑ray state.
The campaign is coordinated by Alexander Salganik, PhD researcher at the University of Turku, Finland, whose work focuses on the Swift/BAT X‑ray light curve of the system. Since 2001 X Persei has shown three major X‑ray outbursts roughly every seven years. The next expected outburst has not occurred, and the source now sits at its lowest X‑ray flux in more than twenty years. Optical monitoring will help determine the current state and physical properties of the Be star’s disk, including whether it remains present or has dissipated during this faint phase.
Spectroscopy: priority is high‑resolution Hα (6563 Å). Additional coverage of He I 6678 Å, He I 5876 Å, or Hβ 4861 Å is welcome. Target cadence is one observation per week.
Photometry: UBVRI is very welcome. If limited, R and V bands are most useful, with R particularly sensitive to disk emission.
Data can be sent directly to Alexander Salganik (alsalganik “at”gmail.com), who will provide regular feedback and campaign updates.
3 July 2025 at 1:42 pm in reply to: GOTO065054.49+593624.51: Discovery of a bright optical galactic transient #630467Robin Leadbeater
ParticipantThe paper is now in A&A and a press release from University of Warwick
(At one point there was a possibility of me appearing on BBC Midlands Today but it was pushed off the list by other events !)
Cheers
RobinRobin Leadbeater
ParticipantI am not sure if the transmission grating (grism) used in the direct vision spectrograph you are using is sensitive to polarisation though.
Transmission gratings are not sensitive to polarisation so that is one thing less to worry about 😉
https://www.edmundoptics.co.uk/f/transmission-gratings/13496
Cheers
RobinRobin Leadbeater
ParticipantOne thing you could do without having to calibrate is to compare the spectrum of the antitwilight sky with that in different directions. Just divide the two spectra to see the difference (Adjust the exposure so the intensity is similar to reduce problems with non-linearity of the camera and be sure to switch off any automatic colour correction in the camera).
Note though that some reflective gratings respond differently depending on the polarisation which changes depending on the direction in the sky. This is an example of the response of a reflection grating. S and P are for the two directions of polarisation. You can also see why you need to consider the grating response as well as the camera QE if you want an absolute flux calibration
https://www.optometrics.com/assets/M466Sales.pngI am not sure if the transmission grating (grism) used in the direct vision spectrograph you are using is sensitive to polarisation though. This shows typical curves for some transmission gratings but it does not show any effect of polarisation.
https://www.optometrics.com/assets/ARTx.png
The one in your spectrograph will probably be similar to the 600l/mm curveCheers
Robin-
This reply was modified 3 months, 1 week ago by
Robin Leadbeater. Reason: typo
Robin Leadbeater
ParticipantYou can approximately calibrate the spectrograph in relative flux using a tungsten lamp of known temperature which will have a black body curve but this will not include the effect of the atmosphere. If you then measure the sun at two different elevations you can then also estimate the effect of the atmosphere. You will need to calibrate the spectrum in wavelength first though
Cheers
Robin-
This reply was modified 3 months, 1 week ago by
Robin Leadbeater.
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This reply was modified 3 months, 1 week ago by
Robin Leadbeater.
Robin Leadbeater
ParticipantNote that even if you know the QE of the camera, this is not enough to flux calibrate the spectrum as there are many other effects between the sun and the camera sensor. The atmosphere and the grating efficiency are the main ones. You need a known light source to flux calibrate spectra. For astronomical spectroscopy this is done by measuring a star with a known spectrum as described in my document here
http://www.threehillsobservatory.co.uk/astro/Relative_flux_calibration_20221222.pdf
but that would not be straightforward with your setup.Can you describe in more detail what you are trying to measure about the solar spectrum ?
Cheers
RobinRobin Leadbeater
ParticipantThe only caveat with these high reflectivity dielectric mirror coatings is that the reflectivity can plummet outside the visible range, particularly into the UV below 4000A. Something to keep in mind if doing spectroscopy at that end of the spectrum.
Robin Leadbeater
ParticipantOnly 10 Lyrids on my NW facing camera last night 21/22nd, though cloud was patchy and completely clouded over by 02:00 UT so probably missed the peak
Robin Leadbeater
ParticipantI just thought it was suspicious to get 3 meteors so close together and parallel within a 30 second period.
Specular reflectance flares from satellite constellations perhaps ?
Cheers
RobinRobin Leadbeater
ParticipantIf it is gas from an eruption it will be interesting to see if it turns into a dark (absorption) feature in UV images once it reaches the sunlit area
Robin
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This reply was modified 10 hours, 13 minutes ago by
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