Blue transient
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Budgieye
moderator
a comet? or dare I say it, Planet X? Too dim to be a flare star or supernova Doesn't quite look like an asteroid.
http://legacysurvey.org/viewer/jpeg-cutout/?ra=223.1852&dec=1.2127&zoom=16&layer=decals-dr3
SDSS and DeCALS comparison
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Would Planet X be moving fast enough for blue-only image?
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Budgieye
moderator
Good point. It should be green-blue if it were.
I'm looking for another asteroid on the same plate to compare, haven't found one yet.
It is on an overlapping brick, if that affects the image. There are 8 blue images. Some sort of slipped image stacking?
CCDs overlapping brick:
decam 425094 N6 g
decam 425094 N7 g
decam 425094 N13 g
decam 425094 N19 g
decam 425095 N1 g
decam 425095 N2 g
decam 425095 N8 g
decam 425095 N14 g
decam 347282 N9 r
decam 347282 N10 r
decam 347282 N15 r
decam 347282 N16 r
decam 347282 N21 r
decam 347282 N22 r
decam 425093 N6 r
decam 425093 N7 r
decam 425093 N13 r
decam 425093 N19 r
decam 425096 N1 r
decam 425096 N2 r
decam 425096 N8 r
decam 425096 N14 r
decam 346927 N9 z
decam 346927 N10 z
decam 346927 N15 z
decam 346927 N16 z
decam 346927 N21 z
decam 346927 N22 z
decam 192972 S4 z
decam 192972 N4 z
decam 193734 N24 z
decam 193762 S26 z
decam 193762 S27 z
decam 193762 S22 z
decam 193762 S16 z
decam 193762 S17 z
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Budgieye
moderator
RA 222 DEC 1, a good enough location for planet Nine
http://www.findplanetnine.com/
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Rick_Nowell
Am I imagining it, but is there a faint source on DSS POSS2 Blue? Using FITS Liberator and colour values:
Black=3466.14, White=5753.58, Zoom=400%
It's faint, but in the right place.
http://archive.stsci.edu/cgi-bin/dss_form
14:52:43.97 +01:12:50.31
PLTLABEL= 'SF06211 ' /Observation: Plate Label
DATE-OBS= '1995-04-24T07:45:00' /Observation: Date/Time
EXPOSURE=62.0 /Observation: Exposure Minutes
TELESCOP= 'Oschin Schmidt - D' /Observatory: Telescope
INSTRUME= 'Photographic Plate' /Detector: Photographic Plate
FITS Liberator 3 software
https://www.spacetelescope.org/projects/fits_liberator/ (very quick download)
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Budgieye
moderator
Wow, a Hubble image!
Well, if it a permanent item, then it can't be a comet / planet. Maybe it is a red dwarf star that occasionally has a blue flare?
What color is a "Red Dwarf"? http://www.galaxyzooforum.org/index.php?topic=279787.msg575925#msg575925
I doubt that it is a voorwerp, with such a rapid change in brightness.
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Rick_Nowell
in response to Budgieye's comment.
As it is the DSS, the image is land-based. The image is taken by the 48" Schmidt Telescope at Palomar and has the FITS Header
TELESCOP= 'Oschin Schmidt - D' /Observatory: Telescope
INSTRUME= 'Photographic Plate' /Detector: Photographic Plate
EMULSION= 'IIIaF ' /Detector: Emulsion
FILTER = 'RG610 ' /Detector: Filter
It must be very hot, otherwise it would show up on the 'red image' as well. SDSS looks like a very red image compared to DECaLS; perhaps SDSS doesn't pick up the wavelength? I don't think it's a star; surely we'd see it in other surveys?
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Budgieye
moderator
Oh, silly me.
A closer look using SDSS
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Rick_Nowell
When using Aladin Lite, none of the surveys shows it, using layers and reversing and all (link below). Very odd. There's not much time difference between DSS and DECaLS surveys; perhaps 15 years?
But, if you look at the direct centre of the SDSS picture above, then to the top of the south-pointing vertical line, just to the left is a black rectangle where the object might be.
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Well, searched everwhere i know including HLA and Subaru but nothing came up, FITS files are beyond my capabilities. Where else can one search?
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Rick_Nowell
Please, FITS are not beyond your capabilities if you have a computer and internet connection. Here's a step-by-step:
- Download FITS Liberator 3 software from https://www.spacetelescope.org/projects/fits_liberator/ (very quick download). You will need 'The ESA/ESO/NASA FITS Liberator 3' as it makes the job a lot easier.
2)Having installed the above software, then go to this address: http://archive.stsci.edu/cgi-bin/dss_form . This is where 'The STScI Digitized Sky Survey' search page is.
3)In front of you is a text-filled page. Half way down there is a "Retrieve from" box. Highlight POSS2/UKSTU Blue. It has to be the blue option!
4)Below the box are where the coordinates are input. Use these: RA 14:52:43.97 DEC +01:12:50.31 (J2000). Further down there is a 'File format' option. Select FITS. GIF won't give you any of the options that you need.
5)Below the format box it has a tab 'RETRIEVE IMAGE'. Click on this and an image like the one I made earlier will take about 10-15 seconds to generate.
6)Now you have the FITS file. Find the zoom just below the picture and select 200%. Then below that, put these figures in the black and white level boxes. Black=3466.14, White=5753.58. Toggle between 300 and 400%. Something is there! Adjust the contrast etc.
7)All the info is on the page marked 'Image Headers'. This will tell you that the image was taken on the 24th of April 1995 using the Oschin Schmidt 48" telescope at Mt. Palomar. The image we are looking at is a 7hr scan of the original photographic plate.
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100% smartphone 😃
But thanks for the seemingly simple step-by-step, think i will dust off laptop to try it some time!
Anymore luck with the blue with FITS from DSS blue?
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Rick_Nowell
Just some thoughts... Some of the objects can be found in SDSS using Navigate. The object to the left is a bright star.
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237651752955478095
The object below is a galaxy. This might not be visible in the DSS FITS as it is very red and low energy/temperature. It wouldn't show up on a high energy image. Indeed there's no obvious trace of it on the DSS FITS image
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237651752955478098
Is it an object in our galaxy, or another further away? I venture we can dismiss asteroids, satellites or comets. Planet X looks unlikely, if only because the DSS and DECaLS image have the object in the same place, yet are ten years apart.
So anything else is guessing! A satellite galaxy of the original galaxy RA: 223.18320 DEC: 1.21399 that has experienced a high-energy event? If in our galaxy, an event to do with the star to the left? A red dwarf flare?
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So thanks Rick for the encouragement!
Unfortunately FITS Liberator tended to crash a lot right after downloading, and the only allowed format to save a file / image is TIFF which doesn't properly save the image as shown in the preview.
But I also downloaded Aladin Desktop at the same time, and learned it can also handle FITS files. Works for me and I think maybe better because it is very easy to use but also has some more handy functions.
Also made a SDSS DR9 + NVSS Contour image so the learning curve can't be that high 😃
(Sure a big images on a PC, but I miss the fast zooming in / out from a smartphone, CTRL + Mouse Wheel just isn't the same)
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JeanTate
in response to Ghost_Sheep_SWR's comment.
Aladin certainly has good tools and capabilities, and learning how to use it is fairly straight-forward.
For the kind of research/analyses you seem to be wanting to do, Ghost_Sheep_SWR, I think you'll find DS9 more appropriate. An awful lot of astronomers use it, and it's been around for quite a while (so you're unlikely to need to deal with bugs). The biggest downside - and it's a pretty big one! - is that the user guide (etc) is often not quite what you'd expect, or need. But hey, if you like tinkering, and treat being frustrated that something you tried didn't work the way you expected as motivation to try again/harder, then I think you'll find the time you spend learning will be richly rewarded.
Hope this helps, and happy hunting! 😃
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Will certainly try thanks for the info!
Btw is there a straightforward method in FITS files viewers (DR9 or other) to get a mag value of objects? Because some objects aren't 'catalogue' objects in SDSS or DECaLS so I can't get a machine-measured value for the magnitude. Haven't found it in Aladin yet.
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JeanTate
in response to Ghost_Sheep_SWR's comment.
Btw is there a straightforward method in FITS files viewers (DR9 or other) to get a mag value of objects?
There are two answers, "yes", and "no" 😮
In DS9, for example, one method is something like this:
- use the Circle region tool
- pick a radius that's not too big nor too small
- with Circle, centered on stars in the field (including your target), obtain the total DN (or other units, depends on the file) for each
- repeat, for the same number of 'blank' regions throughout
- estimate the flux (density; definitions vary!) of each star (basically, total DN minus average 'blank'); take the log
- plot, your estimated log(flux) vs reported for the stars in the field which have published/independently estimated mag
- from an appropriately fitted line (preferably linear, slope=1 ... or is it 4? 0.25?), obtain the relationship
- from the integrated DN of your target object, use the relationship to estimate its mag.
Is that method straight-forward? I think it is, but I suspect many reading this will not.
Also, while this method will certainly give you an estimate of the mag of your target, it may not be sufficiently robust or accurate for your needs.
If your object is not a star (or star-like), I don't think there's a very straight-forward method, not least because deciding what's "not too big, not too small" won't be simple (and you'd be better off using Ellipse rather than Circle).
There are various add-ons (apps, packages, ...) which work with DS9 and which will do a much better job of producing a robust, fairly accurate estimate of magnitude; the downside is that you would have to learn how to use them too (and unlike DS9, they may not be supported on a Windows OS). For example, SExtractor is widely used (by astronomers).
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Fantastic, maybe try SExtractor later on, after DS9. But I might have found a faster method to try and test first.
And to stay on topic, look for this blue one in the different files because it is a curious find.
Thanks very much
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Well astronomers sure make life difficult for themselves, different zipping methods, different orientations etc 😦
No detection in SDSS (all but u band, doesn't work for unknown reason) and DECaLS 2014 images (z and r band). For checking I only used the FITS files that are used in the DECaLS viewer image.
In chronological order:
EDIT dates were all wrong, see next post.
(If interesting enough I might upload images tomorrow)
For all these detections I cannot find any displacement of the transient, so I don't know if this excludes an asteroid because the time window is about 40 minutes. I guess if it is an asteroid or similar if would make it very slow moving?
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Well I got the dates wrong, for some arcane reason they are not included in the FITS Header, but in the DECaLS viewer before downloading the FITS file.
Correct dates for DECaLS images below (in correct order);
- N13-r 15-03-27 07:25:58
- N13-g 15-03-27 07:27:32
- N8-g 15-03-27 07:29:10
- N8-r 15-03-27 07:30:43
So it is actually ~ 5 minutes from first to last image, which would not necessarily exclude an asteroid i guess. I will leave the interpretation open for others 😃
Detection seems better in g band, so that might explain it is (largely) missing in the last r band image.
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What I find strange is that the object is blue although it is visible in both r and g bands.
What would be a typical arcsec movement for an asteroid in 5 minutes anyway, clearly a blue + green image?
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