The study of exoplanets is one of the key tasks of modern astronomy. Exoplanets are planets that exist beyond our Solar System and orbit other stars. One of the most effective methods for their detection is the **transit method**, which is based on recording the decrease in a star's brightness when a planet passes in front of it.

Modern space telescopes such as **Kepler**, **TESS**, and the **James Webb Space Telescope (JWST)** use the transit method to search for and study exoplanets. This method allows not only the discovery of new planets but also the analysis of their physical properties, such as radius, density, and atmospheric composition.

## The Transit Method

### Basic Principles
The transit method involves measuring the decrease in a star's brightness when an exoplanet passes across its disk. The fundamental equation describing the transit depth is:

$$
\Delta F = \left(\frac{R_p}{R_*}\right)^2
$$

where:
- $\Delta F$ — relative decrease in the star's brightness,
- $R_p$ — radius of the planet,
- $R_*$ — radius of the star.

The accuracy of measurements depends on the characteristics of the telescope and the observing conditions. The larger the planet relative to its star, the greater the dimming and the easier it is to detect. However, small planets, similar to Earth, are harder to observe due to the minimal brightness changes they cause.

### Examples of Observed Parameters

| Parameter | Value |
|----------|----------|
| Star radius ($R_*$) | $1.0 R_\odot$ |
| Planet radius ($R_p$) | $1.3 R_\oplus$ |
| Transit depth ($\Delta F$) | 0.00017 (or 0.017%) |
| Orbital period ($P$) | 3.5 days |

### Applications of the Method

The transit method is widely used not only for detecting planets but also for determining their characteristics. For example, if scientists observe multiple transits of the same planet, this allows them to:
- Determine the **orbital period** (the time it takes for the planet to complete one revolution around the star).
- Calculate the **orbital eccentricity** (how elongated or circular the orbit is).
- Study the **planet's atmosphere** using spectroscopy by analyzing the changes in the light spectrum during transit.

## Discovery of Exoplanets

Thousands of exoplanets have been discovered using the transit method, including well-known systems such as **TRAPPIST-1**, which contains seven Earth-like planets, and **Kepler-186**, the first system where a potentially habitable exoplanet was found in the habitable zone ([NASA Exoplanet Archive](https://exoplanetarchive.ipac.caltech.edu/)).

Additionally, this method allows the classification of exoplanets based on their size and composition. For instance, exoplanets are categorized as:
- **Super-Earths** — planets with a radius 1 to 2 times that of Earth.
- **Mini-Neptunes** — planets with a gaseous envelope but smaller than Neptune.
- **Gas Giants** — similar to Jupiter and Saturn in size and composition.

With advancements in technology, exoplanet detection methods continue to improve, and future missions such as **PLATO** (ESA) will allow the discovery of even more new worlds.

## Conclusion

The transit method remains one of the most powerful tools for detecting exoplanets. In combination with other methods, such as the radial velocity method, it provides crucial data on the mass, density, and atmospheres of exoplanets. 

Thanks to advancements in observational astronomy, the number of discovered exoplanets continues to grow, expanding our understanding of planetary system formation and the potential conditions for life beyond Earth. In the future, even more detailed studies of exoplanetary atmospheres and possibly the first signs of extraterrestrial life can be expected.


SAI MSU

Study of Exoplanets Using the Transit Method

Test

Click me

I am good

John Doe

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MASTER-SAAO

South African Astronomical Observatory

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Jane Doe

Hello

string

test

V. Lipunov

V. Kornilov

E. Gorbovskoy

K. Zhirkov

N. Tyurina

P. Balanutsa

A. Kuznetsov

V. Senik

D. Vlasenko

G. Antipov

D. Zimnukhov

E. Minkina

A. Chasovnikov

V. Topolev

D. Kuvshinov

D. Cheryasov

Ya. Kechin

Yu. Tselik

A. Sosnovskij

R. Podesta

C. Lopez

F. Podesta

C. Francile

R. Rebolo

M. Serra

D. Buckley

O. A. Gress

N. M. Budnev

O. Ershova

L. Carrasco

J. R. Valdes

V. Chavushyan

V. M. Patino Alvarez

J. Martinez

A. R. Corella

L. H. Rodriguez

A. Tlatov

D. Dormidontov

V. Yurkov

A. Gabovich

MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB230913.70 (trigger No 1191903, 19h 58m 46.70s, +35d 26m 01.0s, R=0.05) error box 19 sec after notice time and 102 sec after trigger time at 2023-09-13 16:45:58 UTC, with upper limit up to 15.6 mag. Observations started at twilight. The observations began at zenith distance = 18 deg. The sun altitude is -9.3 deg. 

![B-band Lightcurve Photometry](https://www.researchgate.net/profile/Rahman-Amanullah/publication/251507059/figure/fig2/AS:669566371905537@1536648471093/Sample-B-band-light-curve-for-a-z-08-Type-Ia-supernova-Signal-to-noise-targets-are.png)

The galactic latitude b = 3 deg., longitude l = 72 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2269973

We obtain a following upper limits.

```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     113 |      MASTER-Tavrida |   C |    20 | 15.2 |        
     146 |      MASTER-Tavrida |   C |    30 | 15.5 |        
     190 |      MASTER-Tavrida |   C |    10 | 15.1 |        
     201 |      MASTER-Tavrida |   C |    10 | 15.1 |        
     222 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     243 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     265 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     291 |      MASTER-Tavrida |   C |    30 | 15.6 |     
   
     Filter C is a clear (unfiltred) band. 
```

The observation and reduction will continue. The message may be cited.

Fermi-LAT gamma-ray observations of IceCube-220822A and detection of a new source

MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB230913.70 (trigger No 1191903, 19h 58m 46.70s, +35d 26m 01.0s, R=0.05) error box 19 sec after notice time and 102 sec after trigger time at 2023-09-13 16:45:58 UTC, with upper limit up to 15.6 mag. Observations started at twilight. The observations began at zenith distance = 18 deg. The sun altitude is -9.3 deg. 

The galactic latitude b = 3 deg., longitude l = 72 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2269973

We obtain a following upper limits.

```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     113 |      MASTER-Tavrida |   C |    20 | 15.2 |        
     146 |      MASTER-Tavrida |   C |    30 | 15.5 |        
     190 |      MASTER-Tavrida |   C |    10 | 15.1 |        
     201 |      MASTER-Tavrida |   C |    10 | 15.1 |        
     222 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     243 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     265 |      MASTER-Tavrida |   C |    20 | 15.5 |        
     291 |      MASTER-Tavrida |   C |    30 | 15.6 |     
   
     Filter C is a clear (unfiltred) band. 
```

The observation and reduction will continue. The message may be cited.

MASTER

Fermi-LAT gamma-ray observations of IceCube-220822A and detection of a new gamma-ray source, Fermi J1810.1+2154

O.A. Gress

The high redshift (z~2.1) flat spectrum radio quasar (FSRQ) 4C+01.02 **(ICRS coordinate. (ep=J2000): RA 01 08 38.77, Dec +01 35 00.3)** was observed by Fermi-LAT in gamma-ray (>100 MeV) in high activity state (https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/4C+01.02 86400 1yr.png). Following the gamma-ray bright state, X-ray observations of the source were triggered with Swift-XRT. The proposed observation was conducted from September 1, 2022 (11:52:00 UTC), to September 2, 2022 (08:34:00 UTC), in the photon counting (PC) mode for a net exposure of 1.1 Ks. The ToO observation suggests that the source is in the bright state in the X-ray band. The preliminary analysis has been performed fitting the X-ray spectrum with an absorbed power-law considering the galactic absorption corresponding to hydrogen column density of N_H=2.42 x 10^20 cm^-2 (Kalberla et al. 2005, A&A, 440, 775). The observed X-ray (0.3-10 keV) flux on September 1, 2022, is found to be 4.21(+0.80,-0.80) x 10^-12 erg cm^-2 s^-1 is one of the highest flux states of the source. The power law spectral index during this observation is 1.43 (+0.41, -0.41). In light of ongoing activity in Swift-XRT, we encourage further multiwavelength observation of 4C+01.02 (PKS 0106+01, OC 12). We thank the Swift Team and Observatory Duty Scientists who made these observations possible.

MASTER-Amur Robotic Telescope

Swift XRT observations of the high redshift (z=2.1) flat spectrum radio quasar 4C+01.02

Anton

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This is supertest

### Mathematics -->

This is <b>formulae</b>: $e = mc^2$

$$
\displaystyle f''(x) = \lim_{\Delta x \to 0} \frac{f(x+\Delta x) - f(x)}{\Delta x} 
$$


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``` js
var foo = function (bar) {
  return bar++;
};

console.log(foo(5));
```

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| engine | engine to be used for processing templates. Handlebars is the default. |
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Right aligned columns

| Option | Description |
| ------:| -----------:|
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Markdown test

Goophy

MASTER OT J172704.87-163544.4 discovery

V.Lipunov (Lomonosov MSU), E.Gorbovskoy, N.Tiurina, P.Balanutsa, A.Kuznetsov,
V.Kornilov, O.Gress, K.Ivanov, V.Vladimirov, D.Kuvshinov (Lomonosov Moscow
State University, SAI)

MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
 discovered OT source at (RA, Dec) = 17h 27m 04.87s -16d 35m 44.4s on 2023-09-16.11803 UT.

The OT magnitude in 'BLANK' filter is 16.6m
(mlim16.4=).

The OT is seen in 38 images. There is no minor planet at this place.

We have reference image on 2018-04-16.25163 UT with 'BLANK' filter 18.1m.

Spectral observations are required.


NASA

Привет!

The high redshift (z~2.1) flat spectrum radio quasar (FSRQ) 4C+01.02 (ICRS coordinate. (ep=J2000): RA 01 08 38.77, Dec +01 35 00.3) was observed by Fermi-LAT in gamma-ray (>100 MeV) in high activity state (https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/4C+01.02 86400 1yr.png). Following the gamma-ray bright state, X-ray observations of the source were triggered with Swift-XRT. The proposed observation was conducted from September 1, 2022 (11:52:00 UTC), to September 2, 2022 (08:34:00 UTC), in the photon counting (PC) mode for a net exposure of 1.1 Ks. The ToO observation suggests that the source is in the bright state in the X-ray band. The preliminary analysis has been performed fitting the X-ray spectrum with an absorbed power-law considering the galactic absorption corresponding to hydrogen column density of N_H=2.42 x 10^20 cm^-2 (Kalberla et al. 2005, A&A, 440, 775). The observed X-ray (0.3-10 keV) flux on September 1, 2022, is found to be 4.21(+0.80,-0.80) x 10^-12 erg cm^-2 s^-1 is one of the highest flux states of the source. The power law spectral index during this observation is 1.43 (+0.41, -0.41). In light of ongoing activity in Swift-XRT, we encourage further multiwavelength observation of 4C+01.02 (PKS 0106+01, OC 12). We thank the Swift Team and Observatory Duty Scientists who made these observations possible.

O.Ershova

MASTER-Tavrida auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
 discovered OT source at (RA, Dec) = 00h 41m 22.44s +40d 56m 37.9s on 2023-09-13.94319 UT.

The OT magnitude in 'FAULT' filter is 18.4m
(mlim19.6=).

The OT is seen in 12 images. There is no minor planet at this place.

We have reference image on 2023-08-27.99131 UT with 'FAULT' filter 19.8m.

Spectral observations are required.


MASTER OT J004122.44+405637.9 discovery

Following the announcement of a new outburst of the symbiotic star V919 Sgr (Munari et al., ATel #15528), on 2022 July 31 we observed V919 Sgr with the Swift satellite. The pointing started at 13:57 UT. The source was well detected in all UVOT filters, yielding the Vega-system magnitudes reported in the Table below (errors +/-0.07 mag). It was instead not detected in X-rays: a simultaneous XRT observation lasting about 1700 s did not reveal any emission in the 0.3-10 keV band down to a 3-sigma limit of 3.3x10-3 counts s-1. For the distance and reddening listed below, and assuming a kT=0.1 keV bremsstrahlung, this corresponds to <4x10-13 erg/cm2/s in flux and <1x1033 erg/s in LX luminosity.




    To extend the photometric coverage to the optical range, we also observed V919 Sgr with the Asiago 67/92cm Schmidt telescope. The resulting UBVRI magnitudes are listed in the table below (errors <0.005 mag). We have also obtained on Aug 5.959 UT a near-UV, medium-resolution, high S/N spectrum of V919 Sgr with the Asiago 1.22m+B&C telescope, covering the 3190-4400 Ang at 0.58 Ang/pix. The only feature visible in emission is a feeble Hgamma, with Hdelta exactly filling the absorption from the underlying continuum spectrum which is best described as a forest of very sharp absorption atomic lines, so tightly packed that the "true" continuum emerges only at a few pixels sparsely distributed over the recorded spectral interval.




    2022 UT UVW2  UVM2  UVW1  U B V R I
    Jul 31.581        12.63   12.78   11.89         
    Aug 02.904        11.004  11.127  10.573  10.056  9.313
    Aug 03.905        10.988  11.125  10.563  10.051  9.311
    The distance to V919 Sgr is determined by Gaia DR3 in 4.6 kpc (4.0-5.5 kpc limits). The high Galactic latitude (-10deg) favors a low reddening, determined in E(B-V)=0.19 by averaging the results of Marshall et al. (2006, A&A 453, 635) and Green et al. (2019, ApJ 887, 93). After subtracting the contribution of the non-variable M3III giant and dereddening by E(B-V)=0.19, the luminosity radiated by the hot component in the UVOT-UBVRI range is 4.27 x 1036 erg/s (3.20 x 1036 and 5.96 x 1036 at lower and upper limits to Gaia distance). V919 Sgr belongs to the group of symbiotic stars characterized by stable nuclear burning on the surface of the WD. The large luminosity radiated at optical and near-UV wavelengths during the present outburst (1100 Lsun) and the drastic drop in the ionization conditions described by Munari et al. (ATel #15528), support the idea that the outburst was caused by a shift toward optical wavelengths of the emission from the WD, driven by an expansion in radius of its burning shell and fueled by a possible surge in mass-transfer from the M3III companion or the accretion disk.




    Flickering is ubiquitous in accreting-only symbiotic stars (Luna et al. 2013, A&A 559, A6) and absent for the burning variety (Sokoloski 2003, ASPC 303, 202). During the UBVRI observations of V919 Sgr on Aug 2 and 3, we have collected sparse U-band data distributed over 1.5 hours intervals on both nights, and found the U-band brightness stable to better than 0.01 mag. The absence of flickering agrees with the inferred nuclear burning on the WD.




    We thank the Swift Team for the quick approval, scheduling and acquisition of the observation presented in this communication.

Luminosity radiated by the symbiotic star V919 Sgr in outburst, as derived from ground-based and Swift observations

Negoro et al (ATel #15586) report the MAXI detection of an outbursting source in M15. On September 3rd, 2022 at 13:09UT, Swift performed a target-of-opportunity observation of the source, with a 1ks observation taken with XRT in Photon Counting (PC) mode. We find a bright source at the following location: RA/Dec(J2000) = 322.49242, 12.16698 which is equivalent to: 




    RA(J2000) = 21h 29m 58.18s, 
    Dec(J2000) = +12d 10m 01.1s, 




    with an error radius of 2.4 arc-seconds (90% confidence). We note that this position lies 2.3 arc-seconds from M15 X-2, consistent with its location, AC211 lies 2.6 arc-seconds from this position just outside of the error circle (positions from White and Angelini, 2001). Therefore, we cannot from these data alone identify which of these sources are in outburst.




    The spectrum of is well fit by an absorbed power-law model with absorption N_H = 2.0 +/- 0.3 x 10^21 cm^-2 and photon index 1.89 +/- 0.1. The flux, corrected for pile-up and absorption is 1.54 +/- 0.08 x 10^-9 erg/s/cm^2 (0.3 - 10 keV , which is equivalent to a luminosity of ~2 x 10^37 erg/s (0.3 - 10 keV) assuming an 10.9 kpc distance to M15.

Swift confirms outburst of transient in M15

Astro Data Network

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