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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"

28255 results found.

  1. GRB 250309B: PRIME near-infrared detection
  2. GRB 250225B: Swift-BAT refined analysis
  3. GRB 250311A/EP250311a: TRT optical upper limit
  4. EP250311a/GRB 250311A: EP-WXT detection
  5. GRB 250311B: SVOM detection of a burst
  6. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  7. GRB 250309B / AT2025dws: further SAO RAS optical observations
  8. EP250308a: 1.6m Mephisto optical upper limits
  9. Konus-Wind detection of GRB 250309B
  10. IPN triangulation of GRB 250308A (short)
  11. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  12. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  13. GRB 250309B: Swift-XRT refined Analysis
  14. GRB 250309B / IceCube-250309A: GECAM-B observations
  15. GRB 250309B / AT2025dws: SAO RAS optical observations
  16. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  17. GRB 250309B: Fermi GBM Observation
  18. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  19. IceCube-250309A: No candidates from the Zwicky Transient Facility
  20. Fermi-LAT gamma-ray observations of IceCube-250309A
  21. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  23. EP250308a: GSP optical upper limit
  24. EP250308a: Einstein Probe detection of an X-ray transient
  25. EP250308a: NOT optical upper limit
  26. GRB 250306A: EIRSAT-1 GMOD detection
  27. GRB 250306A: Swift-BAT refined analysis
  28. GRB 250306A: NuSTAR detection of the prompt emission
  29. EP250304a: MeerKAT detection of a possible radio counterpart
  30. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  31. GRB 250305A: AstroSat CZTI detection
  32. EP250302a:Xinglong optical observations
  33. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  34. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  35. GRB250101A: Radio upper limits from VLA observations
  36. GRB 250305A: SVOM/GRM observation of a burst
  37. The EP-WXT trigger 01709132323 is likely a flaring star
  38. EP250304A: Upper limits from Fermi-GBM Observations
  39. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  40. EP250302a: Optical Observations at CrAO and SAO RAS
  41. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  42. EP 250304A: Optical counterpart detection by LCO
  43. EP250302A: 1.3m DFOT optical afterglow detection
  44. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  45. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  46. EP250304a: REM NIR upper limits
  47. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  48. EP250302a: Mondy Continued Optical Observations
  49. EP250304a: Swift-XRT detection of a fading X-ray source
  50. EP250304a: TRT optical counterpart detection
  51. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  52. EP250304a: Einstein Probe detection of an X-ray transient
  53. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  54. EP250302a: SAO RAS optical observations
  55. EP250302a : GIT optical follow-up
  56. EP250225a: the candidate optical counterpart is an AGN
  57. EP250302a: Kinder optical follow-up observations
  58. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  59. EP250302a: Swift/UVOT detection
  60. EP250302a: optical observation from the INAF Asiago Observatory
  61. EP250302a: REM NIR upper limits
  62. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  63. EP250302a: Mondy Observations and Optical Light Curve
  64. EP250302a: VLT/MUSE optical redshift z = 1.131
  65. EP250302A: VLT near-infrared observations
  66. EP250302A: VLT/X-shooter tentative redshift
  67. EP250302a: OHP/T193 optical and spectroscopic observations
  68. EP250302a: Swift-XRT observations of a fading X-ray source
  69. EP250302a: Einstein Probe detection of an X-ray transient
  70. EP250302a: SVOM/C-GFT optical observations
  71. GRB 250226A: GRANDMA Optical Observations
  72. EP250302a: Montarrenti Observatory optical detection
  73. EP250302a: Nanshan/HMT optical counterpart detection
  74. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  75. GRB 250225B: VLT near-infrared afterglow confirmation
  76. EP250228a: Optical observations with Kinder and Swift/UVOT
  77. Konus-Wind detection of GRB 250226A
  78. GRB 250225B: EIRSAT-1 GMOD Detection
  79. GRB 250226A: KAO Optical Upper Limit
  80. GRB 250226A: AbAO AS-32 Optical Upper Limit
  81. EP250227a: Global MASTER-Net observations report
  82. EP250223A: Upper limits from Fermi-GBM Observations
  83. EP250227a: TRT optical upper limit
  84. GRB 250225B: VLT/HAWKI near-infrared observations
  85. EP250227a: Optical upper limits with Kinder observations
  86. EP250227a: NOT optical observations
  87. EP250227a: Einstein Probe detected of a fast X-ray transient
  88. EP250228a: updates on the EP observations
  89. GRB 250226A: Fermi GBM Observation
  90. EP250223a: J band upper limit by SYSU 80cm telescope
  91. EP250228a: Swift/XRT localisation
  92. EP250228a: Einstein Probe detection of an X-ray transient
  93. GRB 250226A / EP250226a: LCO detection of the afterglow
  94. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  95. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  96. GRB 250225B: VLT/Xshooter imaging
  97. GRB 250205A / EP250205A: further radio observations with the VLA
  98. EP250225a: NOT optical candidate counterpart
  99. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  100. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations

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