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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"

20551 results found.

  1. GRB 250317B: NOT optical observations suggest an optical plateau phase
  2. GRB 250317B: OHP/T193 optical observations
  3. GRB250312A: Swift/UVOT Upper Limits
  4. GRB 250317B: REM optical/NIR observations
  5. GRB 250316A: Swift/UVOT Upper Limits
  6. GRB 250314A: REM optical/NIR upper limits
  7. GRB 250316A: AbAO AS-32 Optical Upper Limit
  8. EP 250317B: Fading optical counterpart detection by LCO
  9. GRB 250316A: Swift-XRT afterglow detection
  10. GRB 250317B: LCO detection of the fading optical afterglow
  11. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  12. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  13. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  14. GRB 250317B: SVOM detection of a burst
  15. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 250314A: Swift/UVOT Upper Limits
  17. GRB 250314A: Swift XRT Detection
  18. EP250315a: optical counterpart candidate detected by Gemini North
  19. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  20. EP250315a: Einstein Probe detection of an X-ray transient
  21. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  22. SVOM/MXT upper limit on GRB 250314A
  23. GRB 250314A: SVOM/VT upper limit
  24. GRB 250314A: NOT near-infrared candidate counterpart
  25. GRB 250313A: Fermi GBM Detection
  26. GRB 250313A: Swift-XRT observations
  27. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  28. Konus-Wind detection of GRB 250313A
  29. GRB 250314A: SVOM detection of a burst
  30. EP250304a: Pan-STARRS r and i-band imaging and photometry
  31. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  33. GRB 250312A: Enhanced Swift-XRT position
  34. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  35. GRB 250312A: Swift detection of a burst
  36. GRB 241213A: VIRT Optical Upper Limit
  37. GRB 241228A: VIRT Optical Upper Limit
  38. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  39. GRB 250311A: Swift-XRT observations
  40. GRB 250309B: 1.3m DFOT Optical observations
  41. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  42. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  43. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  45. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  46. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  47. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  48. GRB 250309B: PRIME near-infrared detection
  49. GRB 250225B: Swift-BAT refined analysis
  50. GRB 250311A/EP250311a: TRT optical upper limit
  51. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  52. EP250311a/GRB 250311A: EP-WXT detection
  53. GRB 250309B / AT2025dws: further SAO RAS optical observations
  54. EP250308a: 1.6m Mephisto optical upper limits
  55. IPN triangulation of GRB 250308A (short)
  56. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  57. GRB 250309B / AT2025dws: SAO RAS optical observations
  58. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  59. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  60. IceCube-250309A: No candidates from the Zwicky Transient Facility
  61. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  62. EP250308a: Einstein Probe detection of an X-ray transient
  63. EP250308a: NOT optical upper limit
  64. EP250304a: MeerKAT detection of a possible radio counterpart
  65. EP250302a:Xinglong optical observations
  66. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  67. GRB250101A: Radio upper limits from VLA observations
  68. GRB 250305A: SVOM/GRM observation of a burst
  69. EP250302a: Optical Observations at CrAO and SAO RAS
  70. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  71. EP 250304A: Optical counterpart detection by LCO
  72. EP250302A: 1.3m DFOT optical afterglow detection
  73. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  74. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  75. EP250304a: REM NIR upper limits
  76. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  77. EP250302a: Mondy Continued Optical Observations
  78. EP250304a: VLT/X-shooter redshift z = 0.200
  79. EP250304a: TRT optical counterpart detection
  80. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  81. EP250304a: Einstein Probe detection of an X-ray transient
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  83. EP250302a: SAO RAS optical observations
  84. EP250302a : GIT optical follow-up
  85. EP250302a: Kinder optical follow-up observations
  86. EP250302a: Swift/UVOT detection
  87. EP250302a: NUTTelA-TAO Early Measurments
  88. EP250302a: optical observation from the INAF Asiago Observatory
  89. EP250302a: REM NIR upper limits
  90. EP250302a: Mondy Observations and Optical Light Curve
  91. EP250302a: VLT/MUSE optical redshift z = 1.131
  92. EP250302A: VLT near-infrared observations
  93. EP250302A: VLT/X-shooter tentative redshift
  94. EP250302a: OHP/T193 optical and spectroscopic observations
  95. EP250302a: Einstein Probe detection of an X-ray transient
  96. EP250302a: SVOM/C-GFT optical observations
  97. GRB 250226A: GRANDMA Optical Observations
  98. EP250302a: Montarrenti Observatory optical detection
  99. EP250302a: Nanshan/HMT optical counterpart detection
  100. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations

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