# Tag Info

6

TL;DR: There was apparent 11% increase of Neptune brightness during 1980 and 2000. This could be due to multiple reasons. Recent observation suggested the reason to be change in the amount and brightness of the banded cloud mostly in the planet's southern hemisphere due to seasonal variations and thus affect overall brightness of the planet. Neptune's ...

5

What matters is how many photons you collect versus how many you would expect to see if the object wasn't there. Photons would be present, without a source, for a variety of astrophysical (e.g. diffuse background) or non-astrophysical (night sky brightness, dark current) reasons, so you need to be able to rule out the null hypothesis that what you have seen ...

4

To calculate a "luminosity light curve" from a time series of V-band photoetry, you need two things. You need to know the distance. The distance to Betelgeuse is uncertain and that means the absolute value of the luminosity you get will also be shifted systematically up or down by whatever distance you adopt. The V-band only contains a small ...

4

Actually, the very first binary asteroid was discovered by stellar occultation in 1980. The evidence was rejected by the IAU, and wikipedia credits the first binary asteroid discovery to the Galileo spacecraft finding the moon of 243 Ida in 1993. The first moon of the well known asteroid 216 Kleopatra was observed through stellar occultation in 1980. From ...

3

I am the discoverer of delta Velorum's variability (along with the Galileo spacecraft) and I detected those variations visually, so yes, they can be observed, and they are really fun! If you go to the AAVSO VSX page of the star, you have a button called ephemeris that will produce a list of eclipses with their times of beginning - mideclipse - and end. I ...

3

Yes it varies in the visible spectrum. The paper The nearby eclipsing stellar system δ Velorum describes why this is difficult target. Surprisingly it is because it is so bright. The absolute brightness of a star will vary significantly due to absorbtion in the atmosphere. If the sky is slightly hazy, then the stars will be dimmer. To measure the ...

3

The absolute magnitude of an object is defined as the brightness of the object observed at a distance of $d = 10\,\mathrm{pc}$. With this distance, you can convert the luminosity density $L_\nu$ in $\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{Hz}^{-1}$ to a flux density $f_\nu$ in $\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}\,\mathrm{Hz}^{-1}$: $$f_\nu = \... 3 The on- vs. off-band filter is to let you easily measure the strength of an absorption or emission line in the object's spectrum. "Off-band" doesn't refer to a shift in position, but rather in the wavelength that the filter lets through. It is "off" the wavelength of a particular spectral line. This illustrates the idea: (from Michael ... 3 For Gaia EDR3： Note (G1): Note on magnitude errors: They are obtained with a simple propagation of errors with the formulas e_Gmag = sqrt((-2.5/ln(10)*e_FG/FG)**2 + sigmaG_0**2) e_GBPmag = sqrt((-2.5/ln(10)*e_FGBP/FGBP)**2 + sigmaGBP_0**2)) e_GRPmag = sqrt((-2.5/ln(10)*e_FGRP/FGRP)**2 + sigmaGRP_0**2)) with the G, G_BP, G_RP zero point uncertainties ... 3 That is because what is measured is a flux and the flux errors are in the DR2 catalogue. Since magnitudes are based on the logarithm of the flux, then there is no straightforward correspondence (although it matters little if the error bars are less than a few hundredths if a magnitude). Simple error propagation formulae give$$|\Delta G| \simeq \frac{2.5}{\...

2

This is an incomplete answer—a placeholder for a more complete answer that I'm adding here at the request of the OP (who, I will say, has been very patient with me!). Although the precise reasons aren't well understood, I don't think people find the observed brightening of Neptune to be especially anomalous. We have accurate photometry for Neptune for only ...

2

I don't really understand all the equations you wrote out and I'm not sure you can perform the simplification the way you suggest. In particular, I don't agree with Equations (3) and (4). Indeed, using Bayes theorem in the bottom term of Equation (1) leads to  \int_{z_{min}}^{z_{max}} \int_{z_i^-}^{z_i^+} dz dz_p n(z) p_{ph} (z | z_p)\frac{p_{ph}(z_p)}{...

2

I installed eleonor and ran your code - similar but deleted the line: eleanor.Update(sector=1) Because it was giving me an error. And it runs without issues. Attached I post my output. I’m guessing you must have some problems with the packages themselves. I can't pinpoint what, but my naive advice would be to create a conda environment (I can try and help ...

1

No there isn't if you know nothing else about the star. Knowing the distance doesn't help. Knowing the mass and size of the star (how would you know these without other sources of information?) allows you to estimate what sort of a star it is and therefore you have some idea of the spectrum of that kind of star. Given that as a template, then it is possible ...

1

If an object has a measured brightness, then it's extinction-corrected brightness will always be higher. Hence the extinction-corrected magnitude will always be smaller than the uncorrected (observed) magnitude.

1

It's the magnitude where the average signal-to-noise ratio (I assume that's what j_snr represents) is 3.

Only top voted, non community-wiki answers of a minimum length are eligible