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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28288 results found.

  1. SVOM/MXT upper limit on GRB 250314A
  2. GRB 250314A: SVOM/VT upper limit
  3. GRB 250314A: NOT near-infrared candidate counterpart
  4. GRB 250313A: Fermi GBM Detection
  5. GRB 250312B: Fermi GBM Observation
  6. GRB 250313A: Swift-XRT observations
  7. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  8. GRB 250314A: SVOM detection of a burst
  9. GRB 250313A: AstroSat CZTI detection of a bright long burst
  10. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  11. GRB 250313A: Fermi-LAT detection
  12. EP250304a: Pan-STARRS r and i-band imaging and photometry
  13. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  15. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  16. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  17. GRB 250312A: Swift-XRT refined Analysis
  18. GRB 250312A: Enhanced Swift-XRT position
  19. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  20. GRB 250226B: Fermi GBM Observation
  21. GRB 250302A: Fermi GBM Observation
  22. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  23. GRB 250312A: Swift detection of a burst
  24. GRB 241213A: VIRT Optical Upper Limit
  25. GRB 241228A: VIRT Optical Upper Limit
  26. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  27. GRB 250311A: Swift-XRT observations
  28. GRB 250309B: 1.3m DFOT Optical observations
  29. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  31. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  33. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  34. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  35. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  36. GRB 250309B: PRIME near-infrared detection
  37. GRB 250225B: Swift-BAT refined analysis
  38. GRB 250311A/EP250311a: TRT optical upper limit
  39. EP250311a/GRB 250311A: EP-WXT detection
  40. GRB 250311B: SVOM detection of a burst
  41. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  42. GRB 250309B / AT2025dws: further SAO RAS optical observations
  43. EP250308a: 1.6m Mephisto optical upper limits
  44. Konus-Wind detection of GRB 250309B
  45. IPN triangulation of GRB 250308A (short)
  46. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  47. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  48. GRB 250309B: Swift-XRT refined Analysis
  49. GRB 250309B / IceCube-250309A: GECAM-B observations
  50. GRB 250309B / AT2025dws: SAO RAS optical observations
  51. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  52. GRB 250309B: Fermi GBM Observation
  53. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  54. IceCube-250309A: No candidates from the Zwicky Transient Facility
  55. Fermi-LAT gamma-ray observations of IceCube-250309A
  56. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  58. EP250308a: GSP optical upper limit
  59. EP250308a: Einstein Probe detection of an X-ray transient
  60. EP250308a: NOT optical upper limit
  61. GRB 250306A: EIRSAT-1 GMOD detection
  62. GRB 250306A: Swift-BAT refined analysis
  63. GRB 250306A: NuSTAR detection of the prompt emission
  64. EP250304a: MeerKAT detection of a possible radio counterpart
  65. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  66. GRB 250305A: AstroSat CZTI detection
  67. EP250302a:Xinglong optical observations
  68. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  69. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  70. GRB250101A: Radio upper limits from VLA observations
  71. GRB 250305A: SVOM/GRM observation of a burst
  72. The EP-WXT trigger 01709132323 is likely a flaring star
  73. EP250304A: Upper limits from Fermi-GBM Observations
  74. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  75. EP250302a: Optical Observations at CrAO and SAO RAS
  76. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  77. EP 250304A: Optical counterpart detection by LCO
  78. EP250302A: 1.3m DFOT optical afterglow detection
  79. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  80. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  81. EP250304a: REM NIR upper limits
  82. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  83. EP250302a: Mondy Continued Optical Observations
  84. EP250304a: Swift-XRT detection of a fading X-ray source
  85. EP250304a: TRT optical counterpart detection
  86. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  87. EP250304a: Einstein Probe detection of an X-ray transient
  88. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  89. EP250302a: SAO RAS optical observations
  90. EP250302a : GIT optical follow-up
  91. EP250225a: the candidate optical counterpart is an AGN
  92. EP250302a: Kinder optical follow-up observations
  93. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  94. EP250302a: Swift/UVOT detection
  95. EP250302a: optical observation from the INAF Asiago Observatory
  96. EP250302a: REM NIR upper limits
  97. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  98. EP250302a: Mondy Observations and Optical Light Curve
  99. EP250302a: VLT/MUSE optical redshift z = 1.131
  100. EP250302A: VLT near-infrared observations

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