GRB 220305A

R. Caputo (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU),
J. A. Kennea (PSU), A. Y. Lien (U Tampa), K. L. Page (U Leicester),
D. M. Palmer (LANL) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 16:13:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220305A (trigger=1095215).  Due to a viewing constraint,
Swift did not immediately slew.  The BAT on-board calculated location is 
RA, Dec 107.584, -37.708 which is 
   RA(J2000) = 07h 10m 20s
   Dec(J2000) = -37d 42' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 40 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+46.5
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is R. Caputo (regina.caputo AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB), G.
Cusumano (INAF-IASF PA), P.A. Evans (U. Leicester) and J.P. Osborne (U.
Leicester) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 220305A at 17:03:25.5 UT,
3016.9 seconds after the BAT trigger. Using promptly downlinked data we
find a fading, uncatalogued X-ray source located at RA, Dec 107.59841,
-37.68016 which is equivalent to:
   RA(J2000)  = 07h 10m 23.62s
   Dec(J2000) = -37d 40' 48.6"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 108 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.59 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.1
(+6.60/-5.31) x 10^21 cm^-2 (90% confidence).

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez,
M.L.H.Rodriguez (INAOE, OAGH)

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 220305A ( R. Caputo et al., GCN 31684
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 ) errorbox  5464 sec after notice time and 5486 sec after trigger time at 2022-03-05 17:44:35 UT, with upper limit up to  16.4 mag. Observations started at twilight.  The observations began at zenith distance = 16 deg. The sun  altitude  is -8.2 deg. 

The galactic latitude b = -12 deg., longitude l = 249 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1902942

We obtain a following upper limits.  

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

    5577 |         MASTER-SAAO | P\  |   180 | 16.0 |        
    5776 |         MASTER-SAAO | P\  |   180 | 16.4 |        


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

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1712 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 220305A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 107.59853, -37.68033 which is equivalent
to:

RA (J2000): 07h 10m 23.65s
Dec (J2000): -37d 40' 49.2"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

R. Dunwoody (UCD), J. Mangan (UCD) and C.Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 11:33:20.48 UT on 05 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220305A (trigger 668172805 / 220305481).

The on-ground calculated location, using the GBM trigger
data, is RA = 174, DEC = -34 (J2000 degrees,
equivalent to 11 h 36 m, -34 d 00 '), with a statistical uncertainty
of 1.5 degrees.

The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees.

The GBM light curve consists of three emission episodes, the most
prominent occurring around T0+50s, with a duration (T90) of about
172.8 s (50-300 keV).

The time-averaged spectrum for the first emission episode, from
T0-12.3 to T0+12.3, is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -0.6 +/- 0.5
and the cutoff energy, parameterized as Epeak, is 60.9 +/- 9.1 keV.
The event fluence (10-1000 keV) in this time interval is (6.8 +/-
0.8)E-07 erg/cm^2.

The time-averaged spectrum for the second emission episode, from
T0+39.9 to T0+60.4, is best fit by a Band function with Epeak = 320.7
+/- 35.7 keV, alpha = -0.9 +/- 0.1, and beta = -1.9 +/- 0.1. The event
fluence (10-1000 keV) in this time interval is (1.78 +/- 0.03)E-05.

The time-averaged spectrum for the third emission episode, from
T0+164.9 to T0+193.5, is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -1.3 +/- 0.1
and the cutoff energy, parameterized as Epeak, is 205.2 +/- 42.8 keV.
The event fluence (10-1000 keV) in this time interval is(3.5 +/-
0.3)E-06 erg/cm^2.

The 1-sec peak photon flux measured starting from T0+49.6 s in the
10-1000 keV band is 19.5 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB
Catalog:https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM
Support Page:https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

R. Dunwoody (UCD), J. Mangan (UCD), and C.Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 11:33:20.48 UT on 05 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220305B (trigger 668172805 / 220305481).

The on-ground calculated location, using the GBM trigger
data, is RA = 174, DEC = -34 (J2000 degrees,
equivalent to 11 h 36 m, -34 d 00 '), with a statistical uncertainty
of 1.5 degrees.

The angle from the Fermi LAT boresight at the GBM trigger time is 35
degrees.

The GBM light curve consists of three emission episodes, the most
prominent occurring around T0+50s, with a duration (T90) of about
172.8 s (50-300 keV).

The time-averaged spectrum for the first emission episode, from
T0-12.3 to T0+12.3, is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -0.6 +/- 0.5
and the cutoff energy, parameterized as Epeak, is 60.9 +/- 9.1 keV.
The event fluence (10-1000 keV) in this time interval is (6.8 +/-
0.8)E-07 erg/cm^2.

The time-averaged spectrum for the second emission episode, from
T0+39.9 to T0+60.4, is best fit by a Band function with Epeak = 320.7
+/- 35.7 keV, alpha = -0.9 +/- 0.1, and beta = -1.9 +/- 0.1. The event
fluence (10-1000 keV) in this time interval is (1.78 +/- 0.03)E-05.

The time-averaged spectrum for the third emission episode, from
T0+164.9 to T0+193.5, is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -1.3 +/- 0.1
and the cutoff energy, parameterized as Epeak, is 205.2 +/- 42.8 keV.
The event fluence (10-1000 keV) in this time interval is(3.5 +/-
0.3)E-06 erg/cm^2.

The 1-sec peak photon flux measured starting from T0+49.6 s in the
10-1000 keV band is 19.5 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB
Catalog:https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM
Support Page:https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez,
M.L.H.Rodriguez (INAOE, OAGH)

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 220305A ( R. Dunwoody et al., GCN 31689
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 ) errorbox  56245 sec after notice time and 56274 sec after trigger time at 2022-03-06 03:11:15 UT, with upper limit up to  18.3 mag. The observations began at zenith distance = 25 deg. The sun  altitude  is -46.7 deg. 

The galactic latitude b = 26 deg., longitude l = 287 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1902853

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   56305 | 2022-03-06 03:11:15 |         MASTER-OAFA | (11h 29m 45.56s , -35d 27m 42.1s) |   C |    60 | 15.9 |        
   58403 | 2022-03-06 03:46:13 |         MASTER-OAFA | (11h 29m 45.60s , -35d 28m 47.3s) |   C |    60 | 18.3 |        
Filter C is a clear (unfiltred) band. 


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

V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU),
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A.
Melandri (INAF-OAB) and R. Caputo report on behalf of the Swift-XRT
team:

We have analysed 6.2 ks of XRT data for GRB 220305A (Caputo et al. GCN
Circ. 31684
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 ), from 3.0 ks to 43.5 ks after the	BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Beardmore et al. (GCN Circ. 31688
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.22 (+0.11, -0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.34 (+0.28, -0.26). The
best-fitting absorption column is  8.3 (+2.0, -1.8) x 10^21 cm^-2, in
excess of the Galactic value of 2.6 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.8 x 10^-11 (9.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     8.3 (+2.0, -1.8) x 10^21 cm^-2
Galactic foreground: 2.6 x 10^21 cm^-2
Excess significance: 5.3 sigma
Photon index:	     2.34 (+0.28, -0.26)

If the light curve continues to decay with a power-law decay index of
1.22, the count rate at T+24 hours will be 7.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x
10^-13 (6.3 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01095215.

This circular is an official product of the Swift-XRT team.

J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team:

Swift-BAT detected GRB 220305A at 16:13:08 UT on 05 March, 2022 (Caputo
et al. GCN 31684
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 ). There was no Fermi-GBM onboard trigger around the
time of the event.
 
An automated, blind search for short gamma-ray bursts below the onboard
triggering threshold in Fermi-GBM identified no counterparts.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals identified a transient most significantly on the 8.192 s
timescale, with a location consistent with the Swift-BAT event and
a signal-to-noise ratio of 17.8, using the standard search protocol.
The GBM targeted search event was found with the highest
significance with a "normal" spectrum (Band function with
Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.

This analysis is preliminary.

[1] Goldstein et al. 2019 arXiv:1903.12597
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Note: Fermi-GBM also detected GRB 220305B at 11:33:20.48 UT on 05 March 2022
which was erroneously named GRB 220305A at the time of its initial publication
(GCN 31689
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 , 31690
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 ). GRB 220305B is a different burst than the one
described here.

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
R. Caputo (GSFC), T. Sakamoto (AGU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220305A (trigger #1095215)
(Caputo et al., GCN Circ. 31684
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 ).  The BAT ground-calculated position is
RA, Dec = 107.610, -37.703 deg which is
   RA(J2000)  =  07h 10m 26.4s
   Dec(J2000) = -37d 42' 09.2"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 25%.

The mask-weighted light curve shows a single-pulse structure that starts
at ~T-15 s, peaks at ~T0, and ends at ~T+11 s. The burst went out of the
BAT FOV at T+225.7 s. T90 (15-350 keV) is 21.12 +- 3.65 sec (estimated
error including systematics).

The time-averaged spectrum from T-15.04 to T+11.02 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.66 +- 0.15.  The fluence in the 15-150 keV band is
2.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T-0.16 sec in the 15-150 keV band is 2.1 +- 0.5 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1095215/BA/