P. Clay Sherrod Oct 12 1:48 PM
----- Original Message -----
From: "Bill Gray pluto@... [guide-user]"
<guide-user@yahoogroups.com>
To: <guide-user@yahoogroups.com>
Sent: Wednesday, October 12, 2016 12:19 PM
Subject: Re: [guide-user] Searching URAT1 Catalogue (and Gaia-DR1)
> Hi Clay,
>
> I am thinking along those lines, yes. There are a few obstacles.
>
> It would take me an unreasonably long time to download 200 GBytes.
> I'd probably get a USB drive, visit someone with a faster connection than
> mine, and get the data. As I mentioned before, once decompressed,
> we'd be looking at about 500 GBytes.
>
> I would probably then figure out a binary format that would fit all
> the data onto a 128 GByte USB 3.0 drive, with the data sorted out from
> its original weird layout into declination zones. It looks as if one can
> purchase a 128-GByte USB 3.0 drive for a bit over $30 US.
>
> As Arild points out, you _could_ use DVDs, but it would be a really
> big stack of them, even after the compression I'd want to do.
>
> Note that this is all at the "thinking about how to do this" stage.
> Also note that because all problematic stars are currently omitted,
> DR1 is mostly of interest to people doing astrometry and photometry;
> it's not too good for star charting or other purposes. (But for
> astrometry, it appears to make every other catalog utterly obsolete.
> And Gaia DR2 is expected to be quite an improvement over DR1.)
>
> -- Bill
>
> On 2016-10-11 22:13, 'P. Clay Sherrod' drclay@... [guide-user] wrote:
>> Bill....do you have plans for Gaia DR1 to be distributed in the loaner DVD
>> program like we did on many other of the catalogs where we can obtain,
>> download
>> and then forward the DVD to the next guy? I think this would be very
>> beneficial
>> for us all.
>>
>> Clay
>> _____
>> Dr. P. Clay Sherrod
>> Arkansas Sky Observatories
>> MPC H45 - Petit Jean Mountain South
>> MPC H41 - Petit Jean Mountain
>> MPC H43 - Conway West
>> http://www.arksky.org/
>>
>> ----- Original Message -----
>> From: "Bill Gray pluto@... [guide-user]"
>> <guide-user@yahoogroups.com>
>> To: <guide-user@yahoogroups.com>
>> Sent: Tuesday, October 11, 2016 7:58 PM
>> Subject: Re: [guide-user] Searching URAT1 Catalogue (and Gaia-DR1)
>>
>>
>>> Hi Ted,
>>>
>>> You can use Go To... Object Name (or just hit Ctrl-B) and Guide will
>>> bring up an "Enter object name:" dialog. In this, you can enter something
>>> resembling
>>>
>>> 2U314-15926
>>> 3UC314-15926
>>> 4U314-15926
>>>
>>> For UCAC2, the "standard" prefix was 2U; for UCAC3, it was 3UC (I
>>> think
>>> somebody was already using 3U for something else); then, with UCAC4, we
>>> went back to 4U.
>>>
>>> That prefix is followed by a "zone number". All UCACs were split into
>>> zones in declination; for UCAC2 and UCAC3, the zones were 0.5 degrees
>>> high.
>>> That made for zone numbers from 1 to 360 for UCAC3. UCAC2 only got up to
>>> about declination +46 or something like that, so the zone numbers stopped
>>> somewhere around 288.
>>>
>>> UCAC4 was split into 0.2 degree strips in declination, so the zone
>>> numbers run from 1 to 900.
>>>
>>> After the zone number, there's a '-', then the number within that zone.
>>>
>>> Just a heads up : as many of you doubtless know, the first data release
>>> for Gaia (Gaia-DR1) has recently been posted. This provides very precise
>>> astrometry and photometry for about a billion stars.
>>>
>>> This will eventually make all other star catalogs obsolete (well, except
>>> for some very bright stars that were saturated in Gaia). There are some
>>> limits at present : Gaia hasn't been observing for very long, so it
>>> essentially
>>> has only measured "where the stars are now". Parallaxes and proper motions
>>> will come in a subsequent release. Gaia-DR1 only gives data for the cleaner
>>> cases; they haven't tried to sort out the tangled situations with double
>>> and multiple stars. Still, it's what we all should be using for (for
>>> example) astrometric reductions, where the fact that only the "best"
>>> positions are given is a benefit, not a drawback.
>>>
>>> There are two other small hitches to Gaia. First, the raw data files,
>>> provided here :
>>>
>>> http://cdn.gea.esac.esa.int/Gaia/gaia_source/csv/
>>>
>>> tip the scales at over 200 GBytes, in compressed form (still larger
>>> once decompressed, about 500 GBytes). The data are split into 5231 files,
>>> each containing 170579 stars (except for the last one, which just contains
>>> the last few leftover stars).
>>>
>>> The second hitch is that the order of the stars looks to be almost
>>> completely random. It isn't; the stars are ordered according to the
>>> HEALPix 'nested' scheme. This is a theoretically elegant scheme that
>>> could speed up access to the data. That's the theory; in practice,
>>> dealing with this is beyond horrible. I expect that all practical use of
>>> the raw data will involve downloading the files and sorting them into
>>> declination zones, similar to all UCACs and Ax.0 and B1.0. (Why ESA
>>> didn't do that in the first place baffles me. I think someone fell in
>>> love with the mathematical elegance of the HEALPix scheme.) Fortunately,
>>> getting the data sorted into declination zones isn't all that difficult.
>>>
>>> However, I expect most of us will _not_ be downloading 200 GBytes and
>>> then keeping it on a half terabyte of hard drive. Instead, we'll just
>>> download Gaia-DR1 data on an "as needed" basis for a given area, from
>>> VizieR. I'll be setting up Guide to do that.
>>>
>>> -- Bill
>>>
>>> On 2016-10-11 16:17, Ted Blank tedblank@... [guide-user] wrote:
>>>>
>>>>
>>>> Hi Bill, when you get a moment could you remind us what formats Guide
>>>> expects
>>>> for the UCAC one through four star designations?
>>>>
>>>> I cannot seem to find any specific examples in the Help files.
>>>>
>>>> Best regards,
>>>> Ted Blank
>>>>
>>>> (603) 817 9814 (cell)
>>>>
>>>> Sent from my iPhone
>>>>
>>>> On Oct 11, 2016, at 3:00 PM, Bill Gray pluto@...
>>>> <mailto:pluto@...> [guide-user] <guide-user@yahoogroups.com
>>>> <mailto:guide-user@yahoogroups.com>> wrote:
>>>>
>>>>>
>>>>>
>>>>> Hi all,
>>>>>
>>>>> The method Denis mentions will work, _if_ the URAT star is among
>>>>> those displayed on-screen. For URAT1, Guide will extract only that
>>>>> area from the binary catalog, expanding it into the ASCII file
>>>>> 'urat.txt'. It is that file which Guide displays, using the TDF
>>>>> (text definition file) system. And it's that file at which Guide
>>>>> will look when you use Go To... Go to .TDF Object command.
>>>>>
>>>>> I put in some extra code so that Go To... Object Name could recognize
>>>>> UCAC-1 through 4 designations, and A1.0 and A2.0 and B1.0 designations,
>>>>> whether the object was on-screen or not. I'll take another look at
>>>>> getting URAT1 similarly recognized.
>>>>>
>>>>> -- Bill
>>>>>
>>>>> On 10/09/2016 03:03 PM, Denis boucherd@...
>>>>> <mailto:boucherd@...> [guide-user] wrote:
>>>>>>
>>>>>>
>>>>>> Try under GO TO, Go To .TDF Object, select URAT1 in user database and
>>>>>> press OK then enter the star number in search window.
>>>>>>
>>>>>> That should work.
>>>>>>
>>>>>> On 09-Oct-16 11:40 AM, stjohnrobinson@...
>>>>>> <mailto:stjohnrobinson@...> [guide-user] wrote:
>>>>>>> Hello Denis,
>>>>>>>
>>>>>>> I think you have misunderstood or I did not make myself clear enough.
>>>>>>>
>>>>>>> I have the URAT1 data set, and have configured Guide to display the
>>>>>>> URAT1 stars successfully, what I am now trying to achieve is to
>>>>>>> correctly format a search term that can be entered into the GOTO
>>>>>>> command: -
>>>>>>>
>>>>>>> i.e 1URAT547-642315 this is a URAT1 star that guide will display,
>>>>>>> amongst many others, however if you then enter the same format into
>>>>>>> the GOTO command, it returns 'Not a valid object'.
>>>>>>>
>>>>>>> I have tried variations on a theme as it where but with out success.
>>>>>>> So thanks for the response, I will have to see if Bill can enlighten
>>>>>>> me!!
>>>>>>>
>>>>>>> best regards
>>>>>>> stjohn
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> ------------------------------------
>>> Posted by: Bill Gray <pluto@...>
>>> ------------------------------------
>>>
>>> To unsubscribe from this group, send an empty email to:
>>> guide-user-unsubscribe@egroups.com
>>> ------------------------------------
>>>
>>> Yahoo Groups Links
>>>
>>>
>>>
>>
>>
>>
>> ------------------------------------
>> Posted by: "P. Clay Sherrod" <drclay@...>
>> ------------------------------------
>>
>> To unsubscribe from this group, send an empty email to:
>> guide-user-unsubscribe@egroups.com
>> ------------------------------------
>>
>> Yahoo Groups Links
>>
>>
>>
>
>
> ------------------------------------
> Posted by: Bill Gray <pluto@...>
> ------------------------------------
>
> To unsubscribe from this group, send an empty email to:
> guide-user-unsubscribe@egroups.com
> ------------------------------------
>
> Yahoo Groups Links
>
>
>