Grant Privett

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  • in reply to: Bad eclipse viewing advice #622153
    Grant Privett
    Participant

    Reading the JAMA link Nick gave, it looks like they think that you might be somehow taken by surprise by the Sun reappearing and instantly damaged.

    Which is kind of weird as the end of totality is always easy to see coming and I must admit I have yet to hear of the Diamond Ring damaging anyone’s eyesight.

    I could only imagine a problem for people whose eyes remained fully dilated (for some medical or pharmaceutically induced reasons) or who were using a telescope/binoculars during the Ring or forced themselves to keep staring after the Ring was over. Other than that, it sounds tosh to me. But, as Nick wisely says, your experience may differ*.

    *Its a bit frustrating that everyone now needs to protect themselves from the wrath (legal or otherwise) of people not thinking about the potential consequences of their own actions.

    in reply to: Preparing for the eruption of T CrB #622152
    Grant Privett
    Participant
    in reply to: February JBAA #621716
    Grant Privett
    Participant

    And it was sealed okay!

    in reply to: February JBAA #621707
    Grant Privett
    Participant

    My journal just arrived!

    in reply to: Forum oddities #621522
    Grant Privett
    Participant

    One of the fora has a latest update by Digital Monk Marketing. But I cannot see it on the list of contributors. Are we being attacked again.?

    in reply to: map of light pollution trends #621513
    Grant Privett
    Participant

    Fear not. Had my checkup last week.

    The corneas yellowing with age is a known thing. The cataracts are of no concern and it will be years before I need an op apparently. Happens to lots of people. Certainly among the oldies of my family. 🙂

    in reply to: map of light pollution trends #621508
    Grant Privett
    Participant

    I too suspect things are worse than they were, though I also try to bear in mind that my eyes are older too. My corneas will be yellower and the first hints of cataracts are probably appearing.

    I certainly notice it takes me longer to light adapt. There are times when the drops used by opticians to dilate the pupils look very attractive.

    But I must admit we did have a stonking night here last month when the stars were crystalline jewels, despite the fact few places are more than 25 miles from a significant town.

    La Palma remains my favourite place on the planet – I’ve never been to Chile. 🙂

    in reply to: map of light pollution trends #621458
    Grant Privett
    Participant

    They push back because they are cheaper and the number of lights replaced is bigger if they use the bluer lights. The number of lights replaced is an easy metric for “progress” achieved.

    Recently, a sports field I occasionally drive to, to take pictures upgraded their lights. I asked if they would be animal/insect/bird friendly and they said “Yes”. 6 months later I got an email from them apologising that the quotes they got back for animal friendly lighting had proved unaffordable for them – a charity. Happily they usually go off about 10pm.

    in reply to: FITS and FIT files suffix #621443
    Grant Privett
    Participant

    Will let you know in a few days. Hope to have a play this weekend.

    I think I last had a play a year or so back and I did the numpy int16 thing (taking care that the values fit in 65536 bins) and it just wrote out a BITPIX=32. I have a feeling I have to force its hand with BSCALE and BZERO explicitly plus there is some option for in effect, “Don’t mess about with BZERO and BSCALE”. It may be you have to – yourself – make sure the image counts are in the range -32768 to 32767…

    If you had code to hand I would be keen to see it.

    in reply to: map of light pollution trends #621423
    Grant Privett
    Participant

    I recently used VIIRS data taken over the last decade to look at the flux recorded for my area of south Wiltshire and found, as I would expect, massive increases from towns like Amesbury. Looking more generally, even at villages, it appears that these are getting brighter too. The glow from Salisbury is spreading outward.

    I tried pointing out to the local lighting officer and my County Councillor that lower colour temperature LEDs were better, as they reduced scattered light in hazy/foggy conditions, but they seemed largely ignorant or believed I was some sort of nut. Plus the manufacturers sell the bluer lights at a lower price.

    Consequently, the green areas of the Philips light pollution map in South Wiltshire have extended and blue areas in Witshire, Dorset and Somerset are shrinking.

    If you stand in the middle of a roundabout in Wiltshire you will be able to read a newspaper down to the fine print.

    I pointed out to a Lighting Engineer that “Guidelines” are only guidelines and not rules. His response was that wouldn’t do him any good if a coroner investigating a road traffic accident asked him why Guidelines were not followed.

    in reply to: FITS and FIT files suffix #621401
    Grant Privett
    Participant

    Silly thought, is it because the FITS header is rather longer. I think it has to be multiples of 2880 bytes or something. I don’t suppose the author of Vphot could have made the assumption that it was always 2880? Saw that once. But only once and 10 years ago.

    in reply to: FITS and FIT files suffix #621393
    Grant Privett
    Participant

    I’ve seen FITS format files that were FIT, FITS, FTS and f and lower case variants thereof. Never encountered any that were not processed.

    Have once come across software that seemed only equipped for 16 bit data – a histogram of 65536 bins was being used.

    Theres some fun for anyone using Python, the Astropy library discourages the writing of 16 bit FITS files and I think it defaults to 32bit.

    in reply to: Deep Sky Webinar #621328
    Grant Privett
    Participant

    The Celestron Origin, a 6″ RASA is a bit more expensive though…

    in reply to: Deep Sky Webinar #621327
    Grant Privett
    Participant

    To see fainter faster and allow a V band filter to be put on the front, thereby supporting photometry.

    in reply to: BAA song #621308
    Grant Privett
    Participant

    Sempiternal is my new word learned today.

    I did go to a Comprehensive.

    in reply to: Deep Sky Webinar #621298
    Grant Privett
    Participant

    Is there any monochrome option for the camera used?

    in reply to: Poor Peregrine #621265
    Grant Privett
    Participant

    Cloudy here tonight….

    in reply to: Poor Peregrine #621205
    Grant Privett
    Participant

    Alas, work got in the way last night. If Peregrine is 18th I probably won’t get it again until it loops back – if the JPL orbit is updated,,,,

    in reply to: Poor Peregrine #621202
    Grant Privett
    Participant

    When I imaged it there didn’t seem to be any tumbling.

    That may change of course.

    If it cannot land, will it stay in this orbit? Is it stable?

    in reply to: True colours of Uranus and Neptune revealed #621181
    Grant Privett
    Participant

    This might be worth a read: MNRAS 527, 11521–11538 (2024)

    18 fun packed pages… https://academic.oup.com/mnras/article/527/4/11521/7511973

    Figure 1 is interesting.

Viewing 20 posts - 1 through 20 (of 452 total)