# Tag Info

41

Naked eye stars are not distributed uniformly in the sky. That is because the median naked eye star is at a distance of 440 light years, and this is far enough away that some of the details of Galactic structure start to become apparent. Most importantly, the density of stars increase towards the Galactic midplane and has a scale height of a few hundred ...

8

Alright I finally finished this program so I could take a look at each tier individually and see for myself. First of all, the projection type does indeed matter, so I will explain it here. It needs to be an equal-area projection. The whole point of the question was about a uniform distribution of stars over the surface of a sphere. In other words, each ...

8

Your approach is completely correct, just note three things: Logarithmic distribution First, since the distribution of masses is logarithmic in nature (as is most other things), be sure to bin them logarithmically. Otherwise you will oversample (undersample) the bins at the low-(high-)mass end. Comoving densities Second, to be able to compare mass ...

7

The programs I am aware of that you could use do require some programming expertise to operate. I would recommend looking at either IRAF (or PyRAF, which uses Python to interface with IRAF), or SPECTRE. Unfortunately, I'm not aware of a "black box" solution where you can just press a button and go. SPECTRE is written in FORTRAN77 and is quite easy to use ...

6

This is a known issue affecting multiple locations in Google Sky, including a region in Orion and this area in Pegasus. If you look closely at the interface, you can see that Google Sky gets its data from preexisting surveys, including the Digitized Sky Survey and the Sloan Digital Sky Survey - Google doesn't operate its own fleet of telescopes (at least not ...

6

You can do it via the astroquery SDSS module; there is a function called query_sql.

5

Yes, there is are two python modules called astropy, and astropysics that both claim to have spectral analysis tools. As a reference, here is a link for resources for astronomers for the python programming language.

5

There are plenty of software and tools available to do what you want: IRAF, by NOAO; MIDAS which is basically very similar to IRAF but developed by ESO; in Python, either astropy or pyRAF (to use IRAF with a Python interface). I would go with some Python tools (Python is more versatile than IRAF or MIDAS that are much more "single-purpose" oriented), to ...

4

Barnard 68 is the first thing that comes to mind for me, it is a little over 10' across and is opaque in the visible spectrum. I'm sure there could be something much larger out there, but like I said, this was the first to come to mind.

4

A combination of algorithm and by committee. The majority of targets are bright, low-mass dwarf stars. The primary goal of TESS is to discover planets by transit, and these targets offer the best chance of that. The way this is done is described by Stassun et al. (2017). This paper summarises how an input catalogue is constructed (from many data sources) ...

4

If you are looking for images of a particular moving object, the Solar System Object Image Search (SSOIS) at the Canadian Astronomy Data Centre (CADC) has indexed the Pan-STARRS collection. You can enter an object name, orbital elements, an arc or an ephemeris and find images of that object. https://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/ssois/

4

There are two main datasets available from the PanSTARRS survey which are available from the archive at MAST/STScI. These are the Object Catalog, a (large) list of parameters such as position, brightness, shape etc (full list of catalog fields) and the Image Cutouts service which, well, cuts out sections of the images. (The survey went over the same patch of ...

4

Assuming you are using single mode fiber, the entrance (mode diameter) is small, usually a few microns (extremes can range from 1 to say 30 microns, but 2-8 microns is common for visible SMF). The only constraint: you have is to get enough light into that small spot. You can do that with a single lens or convex mirror, a microscope, or a telescope, or even ...

4

a) What is the definition of completeness? Completeness is the number of objects in a data set that are detected over the number that exist. In astronomy, completeness is often estimated for a particular apparent magnitude or flux density. As an example, for sources that are as bright as the Sun (-27 magnitude), we have a completeness of 1. That is, we’...

4

Those are almost certainly "ghosts" caused by the internal reflection of light from very bright stars. (That is, the light is reflecting off the insides of the camera, filter, etc.) The pattern is an image of the "entrance pupil" of the telescope, which in practice means the primary mirror + the blockage caused by the secondary mirror and ...

3

NASA missions that have gone beyond their original Prime Mission lifetime, such as TESS, go into the NASA Senior Review process every 3 years. The most recent one of these was the 2019 Senior Review which reviewed Hubble, Chandra, Fermi, NuSTAR, NICER, Swift, Newton-XMM along with TESS. This review panel looks at the whole operation of the mission, whether ...

3

The areas of the sky covered by the major Near Earth Object (NEO) surveys are reported to the Minor Planet Center. You can plot visualizations of that sky coverage data using the sky coverage form where you can filter by depth, date and survey. The raw data is available, after the surveys give permission for it to be released, from the raw data page. This ...

3

The header of a FITS file is ASCII, and points you to further information. Calling head -n 1 example.fits directs you to "'Astronomy and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H". A software to view FITS images is ds9 (yes, that makes it hard to google...). Alternatively, there's skycat. Both can be used to view and do basic ...

3

You should go to the site https://fits.gsfc.nasa.gov/ where you can read about the FITS data format. This site also has utilities for examining and viewing the data. Most of your concerns about this data should be answered by the documentation on this web site.

3

Use the Optical Spectra Query Form. You'll want to set PRIMTARGET to "GALAXY". Here's the list of possible parameters it can return http://skyserver.sdss3.org/dr10/en/help/docs/QS_UserGuide.aspx#Spectroscopy. Note, there is a query limit of 500,000 rows, so you'll have to break up the query since you'll have more spectra than that.

3

BTW if anyone wants a quick and fast query to solution do the following: Go to https://skyserver.sdss.org/dr12/en/tools/search/sql.aspx. Paste a query like this: SELECT s.specobjid, s.ra, s.dec, s.z FROM SpecObj as s WHERE s.z > 0 AND s.z < .18 AND s.ra > 0 AND s.ra < 50 AND s.dec > 0 AND s.dec < 30 Then after downloading a csv file ...

3

SDSS DR12 Catalog Data looks like a good starting point, apparently pretty open to those willing and able to figure it out. Their SciServer Compute site hosts Jupyter notebooks to query CasJobs in SQL. The Large Scale Structure galaxy catalog under BOSS value added catalogs may also be relevant.

3

CMB fluctuations The CMB fluctuations are often analyzed through their power spectrum $P(k)$, which is a measure of the extent to which it is "clumpy" on a given scale $\ell$, with corresponding wavenumber $k = 2\pi/\ell$. The origin of this power spectrum is laid in the very early early Universe, just after the Big Bang, and it is of utmost ...

3

There shouldn't be any correlation. The CMB light that we see is from a spherical region in the early universe. Its homogeneity strongly suggests that the interior of the sphere was just as homogeneous, but we can't actually see CMB light from the interior. The galaxies that we can see formed from matter inside the sphere, and quite far from the edge. ...

2

What do you mean by, "relative to our ability to observe it"? If you have a detector sensitive enough you'll see some light no matter what direction you look, but the level of light will depend on the resolution of your detector. When you look at a patch on the sky, all of the light within one resolution element basically gets lumped in together. Think of ...

2

The Kepler Field had been covered in the near IR by the 2MASS catalog since that covered the entire northern sky. There was also a Smithsonian Institute program called the Kepler Input Catalog program that observed the Kepler field with the 48-inch telescope at the Whipple Observatory on Mount Hopkins, Arizona in the SDSS g, r, i, and z bands plus a custom ...

2

Well I can't give a mathematically based answer. I can only tell that some man-made objects were recorded by sky surveys. E.g. the Rosetta spacecraft was marked as a newly found asteroid by the Catalina Sky survey although the error was corrected quite quickly. Rosetta made an earth flyby at this time so it was pretty close. The SpaceX Tesla will probably ...

2

A spectrum of, say, a star or a galaxy, consists of wavelengths emitted from various physical processes. In the case of the star, there is the blackbody spectrum that reflects the temperature of all of its gas, whether it is hydrogen, helium, or metals. On top of this, there are lines, i.e. emission from certain atomic transitions that are excited and then ...

2

The rudiments of a solution would be take your apparent magnitude limit and work out how far away you can see type Ia supernovae and how far away you can see core collapse supernovae. Within the latter distance, 30% of the supernovae would be type Ia. Beyond that distance, all of the observed supernovae would be type Ia. You then need to be assuming ...

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