Robin Leadbeater

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Viewing 20 posts - 121 through 140 (of 1,210 total)
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  • in reply to: Anyone using ALADIN Desktop (and/or AIJ) ? #623465
    Robin Leadbeater
    Participant

    Hi Peter,

    Yes that is what I am doing (also the icon at the foot of the image frame) It appears to work but the image is just greyed out. lets see if I can attach an example

    in reply to: Alpy 200, what minimum size scope for supernova ID? #622872
    Robin Leadbeater
    Participant

    Hi John,

    I would say 8 inch would be enough to break into this game. Claudio Balcon who is now the leading amateur in this area started successfully using a 0.2m aperture with his similar home built 200l/mm grism slit spectrograph, though he uses a larger 0.4m aperture now.
    https://www.wis-tns.org/search?&page=1&classifier=Claudio%20Balcon
    (The ones before August 2023 are all with the 8 inch)

    I work down to around mag 17.5 normally but there are quite a few candidates that get to around say mag 15.5-16.5 before being classified which should be within reach provided your skies are not too badly light polluted. An 8 inch at f7 is a similar focal length as my C11 running with as standard 0.63 reducer at f5.5 so if your seeing is similar it should match the same 23um slit I am using.

    These are my classifications, most with the ALPY200. I tend to do more follow ups than initial classifications these days but the most recent 2 are official classifications, one at ~mag 17 and another ~mag 15.5 with strong contamination from the galaxy
    https://www.wis-tns.org/search?&classifier=leadbeater

    You’ve probably already seen it but I did a Youtube presentation on it for Shelyak when they brought out the commercial version
    https://www.youtube.com/watch?v=0L6LLn9HjUY&ab_channel=ShelyakInstrumentsTV

    Cheers
    Robin

    in reply to: R Lyrae #622572
    Robin Leadbeater
    Participant

    Here are typical spectra of M5iii in red (R Lyr) and A0v in blue (Vega) with a typical sensor QE curve (black) overlaid, first at equal V magnitude and then with the correct relative magnitudes assuming RR Lyr Vmag =4.0.

    R Lyr is ~ as bright as Vega in the I band but should still look significantly fainter integrated over the response of an unfiltered image. (Unless perhaps close to the horizon where atmospheric extinction would reduce the difference)

    Cheers
    Robin

    in reply to: Preparing for the next eruption of T CrB #622488
    Robin Leadbeater
    Participant

    Here it is in a 1 sec exposure with my finder last night. (Fuzzy with this unfiltered fast achromat due to the high flux in the IR)

    Cheers
    Robin

    in reply to: Bad eclipse viewing advice #622454
    Robin Leadbeater
    Participant

    today

    tomorrow ! I am often told I dont know what day of the week it is, there is the evidence !

    in reply to: Bad eclipse viewing advice #622453
    Robin Leadbeater
    Participant

    Another bit of eclipse viewing stupidity. Apparently Amazon US are refunding people (using the dealers’ money) who bought SeestarS50 smart scopes because it might be dangerous to view the sun through it as the solar filter does not comply with the AAS filter advice !
    https://www.cloudynights.com/topic/917434-seestar-warning-email/

    Hope you have clear skies today over there

    in reply to: Finding good reference stars #622399
    Robin Leadbeater
    Participant

    Hi John,

    This applies when using a standard star spectra eg Pickles in place of an actual measured spectrum and assuming the published spectral type is correct. It depends how accurate you need to be, particularly at the violet end. Francois Teyssier’s Reference Star Finder spreadsheet default setting gives a warning for stars with E(B-V) >0.05 and an alarm >0.1. If you have ISIS you can estimate how much effect it has using the extinction tool on an A0v Pickles spectrum for example. Attached is the error with E(B-V) = 0.1. I suppose you could even correct for the effect, though that is perhaps pushing the use of stars with published classifications but no published spectra a bit far

    If you have a star with a known as measured spectrum like the non dereddened MILES stars for example the extinction does not matter in theory of course, though I would avoid using the MILES stars with very high extinction. Although it was I who first advocated the use of MILES stars back in 2011,
    http://www.spectro-aras.com/forum/viewtopic.php?f=8&t=191
    I have fallen a bit out of love with them as only a few are ideal as reference stars as many are potentially variable.

    An alternative is the larger MELCHIORS set of spectra which are at much higher resolution so could also be used with higher resolution spectrographs like the LHIRES for example.
    https://www.royer.se/melchiors.html
    SpecInti software has a script in its toolbox for extracting them in a form readable by the usual software (note there is a typo, a missing _ in the English version of the script)
    http://www.astrosurf.com/buil/specinti2/specINTI_toolbox2_en.pdf
    and the STAROS campaign website also has an on line extraction tool
    https://search.staros-projects.org/

    Cheers
    Robin

    in reply to: Preparing for the next eruption of T CrB #622346
    Robin Leadbeater
    Participant

    Brad Schaefer talking enthusiastically about T CrB on BBC World Service “Science In Action”
    https://www.bbc.co.uk/sounds/play/w3ct4sdv

    Robin

    in reply to: AT2024epj – A mag 10 transient in/near the LMC #622240
    Robin Leadbeater
    Participant

    Spectra from 2SPOT and Tom Love now posted in the ARAS forum
    http://www.spectro-aras.com/forum/viewtopic.php?p=17753

    in reply to: N 2024 Oph (V4370) #622230
    Robin Leadbeater
    Participant

    A spectrum from 2024-03-12 by the 2SPOT team (amateur remote echelle spectrograph in Chile)
    http://www.spectro-aras.com/forum/viewtopic.php?t=3122

    Very red continuum with very intense, very broad H alpha

    in reply to: Lhires111 #622229
    Robin Leadbeater
    Participant

    I have released the collar. When tightened then slackened a fraction of a turn the micrometer is easier to turn.

    Then I think you have found the cause of the problem. You can slacken it right off. If it turns freely then, there is no overhaul needed. I find the micrometer setting does not move on its own in normal use but if you want to be 100% sure you can always clamp the locking collar back down after you set it at the wavelength you chose. No need to lock it with the grub screw though. That is really for use in an industrial machinery where the micrometer might be used as a set stop which must stay in position under vibration etc

    in reply to: Lhires111 #622218
    Robin Leadbeater
    Participant

    If the locking collar is engaged and you have the locking screw loosened, it could be worth trying to release it first. (Screw anticlockwise) I just tried mine and when the collar is engaged it can be quite tight to then disengage. Try it with your spare, engaging and disengaging the locking collar does not affect the calibration.

    Re lubricant the internet suggests clock oil for micrometers. (not silicone which creeps and could end up on the optics)

    in reply to: Lhires111 #622213
    Robin Leadbeater
    Participant

    If the grub screw was not loose and the locking collar cannot be turned even after loosening the screw it is unlikely that this is the reason that the micrometer had become tight. (Did it suddenly become tight or has it becoming increasingly tight over time). Can you tell from my photos and comparing with the other LHIRES if the collar is engaged or disengaged ?

    Other than that I guess it needs an overhaul, removing it, unscrewing the barrel cleaning and re-lubricating. Mine is still fine after 18 years though (I recall you have a remote adjustment, could this have been preloading it causing premature wear?)

    in reply to: Lhires111 #622202
    Robin Leadbeater
    Participant

    Photos with the collar engaged and disengaged

    in reply to: Lhires111 #622201
    Robin Leadbeater
    Participant

    I just used a Jeweller’s screwdriver but if the grub screw is tight then it seems unlikely that the collar has moved so it probably is not the reason for the micrometer becoming tight. With mine the locking collar is close to the spectrograph body when engaged and there is a definite gap with it disengaged. I will take a couple of photos.

    Cheers
    Robin

    in reply to: Lhires111 #622199
    Robin Leadbeater
    Participant

    There is a knurled collar at the base of the micrometer held in position with a tiny cross head grub screw which is used to lock the micrometer at a given setting. Has that got tightened down? Mine is fully wound off (anticlockwise) and locked down with the grub screw.

    Cheers
    Robin

    in reply to: Is AT2024djo a new mag 13 asteroid? #622030
    Robin Leadbeater
    Participant

    Meanwhile ZTF have “discovered” their second high proper motion star in the past 3 months
    https://www.wis-tns.org/object/2023acmv
    https://www.wis-tns.org/object/2024dum

    Robin

    in reply to: Request for observations of the nearby supernova SN 2024cld #621881
    Robin Leadbeater
    Participant

    That’s odd. According to time on the confirming spectrum on TNS, it was taken a day before the discovery date

    Robin

    Followed this up with the GOTO team. The date of the spectrum was indeed wrong and is now corrected in TNS

    Robin

    in reply to: Request for observations of the nearby supernova SN 2024cld #621842
    Robin Leadbeater
    Participant

    That’s odd. According to time on the confirming spectrum on TNS, it was taken a day before the discovery date

    Robin

    in reply to: M45 by daylight. #621774
    Robin Leadbeater
    Participant

    Stars with H alpha emission lines (of which there are several in the Pleiades) in a narrow band H alpha filter (where the solar spectrum has a deep absorption) might be interesting.

Viewing 20 posts - 121 through 140 (of 1,210 total)