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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"

20554 results found.

  1. GRB 250317C: SVOM/GRM observation of a long burst
  2. GRB 250317B: Leavitt Observatory optical upper limit
  3. GRB 250317B: Mondy AZT-33IK Optical Observations
  4. GRB 250317B: NOT optical observations suggest an optical plateau phase
  5. GRB 250317B: OHP/T193 optical observations
  6. GRB250312A: Swift/UVOT Upper Limits
  7. GRB 250317B: REM optical/NIR observations
  8. GRB 250316A: Swift/UVOT Upper Limits
  9. GRB 250314A: REM optical/NIR upper limits
  10. GRB 250316A: AbAO AS-32 Optical Upper Limit
  11. EP 250317B: Fading optical counterpart detection by LCO
  12. GRB 250316A: Swift-XRT afterglow detection
  13. GRB 250317B: LCO detection of the fading optical afterglow
  14. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  15. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  16. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  17. GRB 250317B: SVOM detection of a burst
  18. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  19. GRB 250314A: Swift/UVOT Upper Limits
  20. GRB 250314A: Swift XRT Detection
  21. EP250315a: optical counterpart candidate detected by Gemini North
  22. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  23. EP250315a: Einstein Probe detection of an X-ray transient
  24. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  25. SVOM/MXT upper limit on GRB 250314A
  26. GRB 250314A: SVOM/VT upper limit
  27. GRB 250314A: NOT near-infrared candidate counterpart
  28. GRB 250313A: Fermi GBM Detection
  29. GRB 250313A: Swift-XRT observations
  30. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  31. Konus-Wind detection of GRB 250313A
  32. GRB 250314A: SVOM detection of a burst
  33. EP250304a: Pan-STARRS r and i-band imaging and photometry
  34. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  36. GRB 250312A: Enhanced Swift-XRT position
  37. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  38. GRB 250312A: Swift detection of a burst
  39. GRB 241213A: VIRT Optical Upper Limit
  40. GRB 241228A: VIRT Optical Upper Limit
  41. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  42. GRB 250311A: Swift-XRT observations
  43. GRB 250309B: 1.3m DFOT Optical observations
  44. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  46. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  48. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  49. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  50. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  51. GRB 250309B: PRIME near-infrared detection
  52. GRB 250225B: Swift-BAT refined analysis
  53. GRB 250311A/EP250311a: TRT optical upper limit
  54. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  55. EP250311a/GRB 250311A: EP-WXT detection
  56. GRB 250309B / AT2025dws: further SAO RAS optical observations
  57. EP250308a: 1.6m Mephisto optical upper limits
  58. IPN triangulation of GRB 250308A (short)
  59. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  60. GRB 250309B / AT2025dws: SAO RAS optical observations
  61. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  62. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  63. IceCube-250309A: No candidates from the Zwicky Transient Facility
  64. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  65. EP250308a: Einstein Probe detection of an X-ray transient
  66. EP250308a: NOT optical upper limit
  67. EP250304a: MeerKAT detection of a possible radio counterpart
  68. EP250302a:Xinglong optical observations
  69. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  70. GRB250101A: Radio upper limits from VLA observations
  71. GRB 250305A: SVOM/GRM observation of a burst
  72. EP250302a: Optical Observations at CrAO and SAO RAS
  73. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  74. EP 250304A: Optical counterpart detection by LCO
  75. EP250302A: 1.3m DFOT optical afterglow detection
  76. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  77. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP250304a: REM NIR upper limits
  79. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  80. EP250302a: Mondy Continued Optical Observations
  81. EP250304a: VLT/X-shooter redshift z = 0.200
  82. EP250304a: TRT optical counterpart detection
  83. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  84. EP250304a: Einstein Probe detection of an X-ray transient
  85. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  86. EP250302a: SAO RAS optical observations
  87. EP250302a : GIT optical follow-up
  88. EP250302a: Kinder optical follow-up observations
  89. EP250302a: Swift/UVOT detection
  90. EP250302a: NUTTelA-TAO Early Measurments
  91. EP250302a: optical observation from the INAF Asiago Observatory
  92. EP250302a: REM NIR upper limits
  93. EP250302a: Mondy Observations and Optical Light Curve
  94. EP250302a: VLT/MUSE optical redshift z = 1.131
  95. EP250302A: VLT near-infrared observations
  96. EP250302A: VLT/X-shooter tentative redshift
  97. EP250302a: OHP/T193 optical and spectroscopic observations
  98. EP250302a: Einstein Probe detection of an X-ray transient
  99. EP250302a: SVOM/C-GFT optical observations
  100. GRB 250226A: GRANDMA Optical Observations

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