Talk:Hale Telescope

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Source[edit]

hello Wikipedia I added a description of the Hale Telescope, partly copied from our website, with permission. Andrew Pickles Associate Director Operations, Caltech Optical Observatories pick@caltech.edu

Mirror[edit]

Forty plus years ago I read the educational comic book about the Palomar Observatory and the Hale Telescope. They told about the first attempt at making the mirror, which was the biggest piece of glass Corning had ever made. The heat of the big pot of glass was so hot that the ceiling was damaged and two bricks fell into the mix. A friend of mine saw this piece of glass in Corning about 15 years ago, and she said it looks perfectly clear, but the astronomers rejected it, so a second glass blank was made and shipped to California. This should be in the article.  Randall Bart   Talk  00:36, 7 April 2009 (UTC)[reply]

Since it's a mirror clarity isn't a concern, just dimensional stability. In any case, the story is true and here's a source: [1]   Will Beback  talk  07:40, 7 April 2009 (UTC)[reply]
I went ahead and added a bit about the mirror and also about the coating process. GFee free to revise and improve.   Will Beback  talk  08:05, 7 April 2009 (UTC)[reply]
Great addition. --ChetvornoTALK 04:56, 9 April 2009 (UTC)[reply]

85.24.143.128 (talk) 15:23, 6 January 2010 (UTC) hmm..."2 millionths of an inch", isn't that 50 nm? [Please remove this comment after correction][reply]

I remember reading about 35 years ago that during transport of the mirror by rail it was protected by a bullet-proof case. Upon arrival near the observatory they found dozens of bullet holes in the case! Interesting material but probably not significant enough to place in the article. If someone thinks it might be deserving of inclusion then comment here and I will look up the documentation.Linktex (talk) 19:21, 9 January 2014 (UTC)[reply]

Discoveries[edit]

Please could somebody add information about important discoveries that have been made primarily with this telescope? Thank you.—RJH (talk) 16:35, 8 October 2009 (UTC)[reply]

Mirror redux[edit]

Consolidated material about the mirror into section and expanded[2]. Deleted the second paragraph since it is wrong about the 200 inch being the 2 largest single mirror, its about the 8th largest according to List of largest optical reflecting telescopes. The rest of the paragraph is unref'ed and more overall descriptive of large mirrors in general than about the 200 inch. It could be added to Reflecting telescope or some other article dealing with large mirrors. Fountains of Bryn Mawr (talk) 17:10, 23 October 2009 (UTC)[reply]

Yes, the section should have said that the Hale and BTA-6 are the largest telescopes in the world with traditional rigid mirrors. It is correct that there are about 8 telescopes with larger single mirrors. As the deleted text explained, these larger mirrors are too big to hold their shape as they are rotated, so their shape is controlled by moveable mounts with complicated computer controlled actuators that compensate for the sagging of the mirror as it is turned. These are essentially flexible mirrors. The Hale and the BTA-6 are notable as the largest telescopes with rigid mirrors that don't require dynamic computer figure correction. However, as you say the material was unsourced. I'll try to find sources. --ChetvornoTALK 04:30, 24 October 2009 (UTC)[reply]
Restored deleted paragraph with supporting citations. --ChetvornoTALK 10:26, 11 November 2009 (UTC)[reply]

First light date should not come from Wikidata[edit]

The source give the first light date as January 26, 1949, 10:06 pm Pacific Time. Wikidata gives it as 26 January 1949. All dates on Wikidata are Universal Time, according to their data model. So the first light of the Hale telescope was January 27, 1949, 6:06 am Universal Time, and the date in Wikidata is wrong. Jc3s5h (talk) 00:14, 18 June 2017 (UTC)[reply]

@Jc3s5h: We should really be using UTC to avoid this kind of confusion! I changed the date on Wikidata this eve to match the article, before making the edit that you reverted. I've since undone that change on Wikidata. The details should be covered in the article text, rather than the infobox (which is why I moved the exact time and the reference to the article text). Does that resolve this issue, or how can we change the programming logic to better handle this? Thanks. Mike Peel (talk) 00:24, 18 June 2017 (UTC)[reply]
UTC IS UNACCEPTABLE BECAUSE IT DID NOT EXIST UNTIL 1960. Since this is an astronomy article, sloppy nomenclature will cast doubt the quality of the entire article. If there is a desire to use a more location-neutral time, it should be Universal Time.
The universal custom in English agrees with MOS:TIMEZONE: "Give dates and times appropriate to the time zone where an event took place." In the absence of any time zone indication, readers will naturally assume the date is a Pacific Time date, and thus thus the article misrepresents the statements of the authors of the cited source. If you want to use Universal Time, it should be labelled UT.
But since we are talking more about a ceremonial event than an entry in an astronomical data book, I believe the date should be in Pacific Time
Furthermore, although the Wikidata data model says they use UT, this requirement is widely violated, and their inability to enter time zones or express times with precision better than a day makes it virtually impossible to obey this requirement. My view is we shouldn't import any dates at all from Wikidata when the precision is better than a month. Jc3s5h (talk) 00:37, 18 June 2017 (UTC)[reply]
@Jc3s5h: My understanding is that UT and UTC is essential the same, particularly on the scale of days. I would like to see Wikidata record times (and timezones) along with days, but they aren't there yet. I'm trying to figure out what will work best here for now - is there a date that we can set on Wikidata that would be acceptable, or should we locally define that parameter until the timing precision improves there? Are there any problems with the other parameters that I converted to Wikidata in the edit that you reverted, or can they be reinstated? Thanks. Mike Peel (talk) 00:43, 18 June 2017 (UTC)[reply]
I don't see any problem with the focal length or mounting parameters; when I made my edit I mistakenly thought they were already there and only the order was changed.
UT is an umbrella term that can encompass all the varieties of UT, such as GMT, UT0, UT1, UT2, and UTC, when the distinctions among them is unimportant. When you want to indicate differences of a few seconds don't matter, UT is the correct term, especially when UTC is incorrect.
I think any date in Wikidata that will be one value if you follow the data model and a different value if you simply copy the value from the source without converting time zones is unstable, as Wikidata goes through the throes of deciding how to fix their broken dates. I wouldn't allow any such date in Wikipedia. Jc3s5h (talk) 01:00, 18 June 2017 (UTC)[reply]
@Jc3s5h: OK, I've partially reverted your revert, but have left the first light locally defined, I hope that's OK. I would encourage you to raise the date issue for discussion on Wikidata, as it would be good to properly resolve this. I know that there are different definitions of UT, my preference would be that we can define the timestamp accurately and that we use programmed logic to covert between timezones/conventions as appropriate. Thanks. Mike Peel (talk) 01:07, 18 June 2017 (UTC)[reply]
I raised it years ago; the developers are largely ignoring the date issues. A list of the time and date related bugs is at https://phabricator.wikimedia.org/T87764 Jc3s5h (talk) 01:20, 18 June 2017 (UTC)[reply]
OK, noted. Hopefully it will be resolved in the long-term, and we can migrate this property to Wikidata properly then. Thanks. Mike Peel (talk) 01:59, 18 June 2017 (UTC)[reply]

HR8799[edit]

It should be said why the star itself is not in the photograph. — Preceding unsigned comment added by 109.153.143.86 (talk) 14:54, 24 August 2017 (UTC)[reply]

External links modified[edit]

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External links modified (January 2018)[edit]

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/* Proposals and precursors */ Resolution also depends on wavelength, so specify optical.[edit]

Observations and research[edit]

This section, as of February 2022, appears to have two problems. It's missing most of the major discoveries (see this list from the builders of Hale) while containing an assortment of references to relatively minor discoveries. I think this should be cleaned up. The paper THE FIRST 50 YEARS AT PALOMAR: 1949–1999 The Early Years of Stellar Evolution, Cosmology, and High-Energy Astrophysics would form an excellent basis for discoveries up to 1999. LouScheffer (talk) 13:32, 12 February 2022 (UTC)[reply]

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