# Tag Info

0

Based on the magazine Ciel et Espace of October-November 2021, it can be done with a small instrument and a narrow-band filter centered on the emission of sodium. They show an image of Mercury's sodium tail made by stacking seven 1-minute pictures from an Astro Professional 80ED refractor telescope and an EOS 500 D. Nul besoin d'un gros instrument pour la ...

4

No For a telescope to be useful, the particles/waves that the telescope detects must reach the telescope. This is why space is a great place to put a telescope: there is nothing, not even air, to block the particles/waves. Light does not penetrate beyond a few mm into the ground, so a telescope in a mine will not get any light from the stars. Bluntly, it ...

1

"AT" are sources named by the transient name server: A name of the form, e.g. 2016ab, defines the object uniquely. Before it is spectroscopically classified it will have a prefix of "AT". If classified as a SN of whichever type, the prefix changes to "SN". "TXS" are sources from the Texas Survey of radio sources: ...

1

There is a question on a related topic: Why aren't new stars in Earth's relative proximity constantly discovered? I quote from my answer: The 1991 third Gleise catalog of stars within 25 parsecs (84.64 light years) of the Sun includes 3,803 stars. A sphere with a radius of 25 parsecs has a volume of 65,449.8469 cubic parsecs. So the stars in the ...

4

Only rough numbers can be given and I would base them on the Gaia EDR3 catalogue since you are demanding that distances are known and no other big catalogue will have parallaxes (and hence distances, since non-parallax-based distances are usually less accurate than 10%). There will be no spherical volume that can be given. The sensitivity of Gaia is a ...

3

I believe that is a typo. In Tables 4 and 5 of the same document, "UVIS 47" is listed as "g280", which is the grism you are curious about. A perusal of several other HST documents (e.g., various Wide Field Camera 3 Instrument Handbooks) turns up no mention of a "G200" element, and searches of the HST archive turn up nothing if &...

3

By offsetting the SCA columns, the Field of View layout follows the natural annular curve of an off-axis TMA optimized field. Short answer: Yes, off axis aberration magic. Longer answer: The following journal article, "Optical design and predicted performance of the WFIRST phase-b imaging optics assembly and wide field instrument" (Bert et al., ...

3

This is, as David Hammen points out, incorrect. However, it's not completely nonsense, either, in that the theoretical studies that led to the 1970s prediction of CFCs damaging the ozone layer -- prior to the observational discovery of the Antarctic ozone hole -- did involve some inspiration from theoretical studies of possible chemical reactions in the ...

2

People who were studying the atmosphere of Venus were actually the ones that discovered the ozone hole on the Earth. I call BS. Being slightly familiar with the discovery of the ozone hole, I have read about the people who did discover the ozone hole. They were British geophysicists. I cannot find a single article by JC Farman, BG Gardiner, or JD Shanklin ...

3

I'm pretty sure it's restricted to the near-IR, with the shortest wavelengths being $Y$-band or $J$-band (i.e., 1 or 1.2 microns) and the longest being $L$-band (i.e., 3.8 microns). This is probably because 1) classical adaptive optics systems use the optical for corrections that are applied in the near-IR (for reasons I discussed in this answer); and 2) ...

3

This is a great question and sampling is always a little tricky. side note: It's important to make sure that no down-conversion has been done, that the " 1000-1400 MHz band" has not already been mixed with a 900 MHz local oscillator and shifted to 100-500 MHz before conversion. I had a hunch that you can get by with a lower frequency. I chose 1000 ...

1

Yes. Chris Brown of the Shetland times writes in Feb 2000: February brings a chance to try and see the elusive planet Mercury. In the week surrounding the 15th Mercury will be setting after the Sun. At best on the 15th at 18:00 it will be just 6 degrees above the horizon. At the same time Mars will be at an altitude of 19 degrees and to the left of Mercury....

7

The spike would be due to the release of a "final" catalogue of Exoplanet candidates discovered in the main Kepler mission, which was issued in July 2015. This list was vetted and a catalogue of about 1300 very likely exoplanets was released by NASA in May 2016. Observations of the Kepler main field ceased much earlier in 2013, but after that the ...

3

It can, and it has been imaged by ground-based photography. Carl Schmidt dedicated his PhD thesis to Mercury and in particular its sodium tail. Therein he describes the setup and procedure. The - to me - most impressive photo was obtained with a 10cm coronograph at the McDonald observatory with a very narrow band-pass filter (around ~1nm width): In essence: ...

4

Yes it can be seen, but as the angle of the ecliptic is lower in more Northern Latitudes it is harder to see. Chris Brown of the Shetland times writes in Feb 2000: February brings a chance to try and see the elusive planet Mercury. In the week surrounding the 15th Mercury will be setting after the Sun. At best on the 15th at 18:00 it will be just 6 degrees ...

2

Hello Random_Astro_Student, If you have not already, refer to this document. Section 14.1.1 provides the schema for gaiasource. You will note that there is no field with a name (eg: 'Alpha Centauri A'). I had queried Gaia data using the function below. GaiaDR2SourceIDs is a comma separated string (ID1,ID2,ID3,.....,IDn) for ID's to retrieve. ...

9

To understand the history of the figure in question it is important to understand some of the context. In the run up to the operation of advanced LIGO, it was widely expected that the first detections would come in the form of relatively weak signals, whose presence in the data could only be established by comparing with theoretical templates through matched ...

5

Phil Plait's blog, Bad Astronomy, answers many of these questions. He reports that it was first spotted in WISE (Wide Field Infra-red Survey Explorer) data looking for Submillimeter bright galaxies, in the AllWISE data, it is just a blob. With follow-up observations by the Atacama Pathfinder Experiment (APEX). You can read the journal article but it is ...

4

This issue is a bit complex, and at its core revolves around the claim of a Copenhagen group led by Andrew Jackson that LIGO data was not handled correctly, a mislabeled plot, and some small (but since resolved) controversy regarding the transparency of LIGO science. When LIGO published their initial findings, they included a plot that was, indeed, adjusted ...

5

Below are some strengths of some radio sources. Let's choose 1000 Jy and 100 MHz bandwidth, a modest 1000 m^2 single dish and 8 hour observation. $$1000 \times 10^{-26} \ \text{W} \text{m}^{-2} \text{Hz}^{-1} \times 1000 \ \text{m}^2 \times 10^8 \ \text{Hz} = 10^{-12} \text{W}$$ and $$10^{-12} \text{W} \times 28800 \text{sec} = 3 \times 10^{-8} \text{J}$$ ...

Top 50 recent answers are included