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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"

21924 results found.

  1. Konus-Wind detection of GRB 250308A
  2. GRB 250314A: SVOM detection of a burst
  3. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  4. EP250304a: Pan-STARRS r and i-band imaging and photometry
  5. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  6. Fermi GRB 250313A: Global MASTER-Net observations report
  7. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  8. GRB 250312A: Enhanced Swift-XRT position
  9. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  10. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  11. GRB 250312A: Swift detection of a burst
  12. GRB 241213A: VIRT Optical Upper Limit
  13. GRB 241228A: VIRT Optical Upper Limit
  14. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  15. GRB 250309B: 1.3m DFOT Optical observations
  16. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  17. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  18. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  19. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  20. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  21. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  22. GRB 250309B: PRIME near-infrared detection
  23. GRB 250225B: Swift-BAT refined analysis
  24. GRB 250311A/EP250311a: TRT optical upper limit
  25. EP250311a/GRB 250311A: EP-WXT detection
  26. GRB 250309B / AT2025dws: further SAO RAS optical observations
  27. EP250308a: 1.6m Mephisto optical upper limits
  28. IPN triangulation of GRB 250308A (short)
  29. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  30. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  31. GRB 250309B / AT2025dws: SAO RAS optical observations
  32. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  33. GRB 250309B: Fermi GBM Observation
  34. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  35. IceCube-250309A: No candidates from the Zwicky Transient Facility
  36. EP250308a: Einstein Probe detection of an X-ray transient
  37. EP250308a: NOT optical upper limit
  38. Konus-Wind detection of GRB 250306A
  39. GRB 250306A: NuSTAR detection of the prompt emission
  40. EP250304a: MeerKAT detection of a possible radio counterpart
  41. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  42. EP250302a:Xinglong optical observations
  43. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  44. GRB250101A: Radio upper limits from VLA observations
  45. GRB 250305A: SVOM/GRM observation of a burst
  46. GRB 250305A: Fermi GBM Final Real-time Localization
  47. EP250302a: Optical Observations at CrAO and SAO RAS
  48. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  49. EP 250304A: Optical counterpart detection by LCO
  50. EP250302A: 1.3m DFOT optical afterglow detection
  51. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  52. Konus-Wind detection of GRB 250222A
  53. EP250304a: REM NIR upper limits
  54. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  55. EP250302a: Mondy Continued Optical Observations
  56. EP250304a: TRT optical counterpart detection
  57. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  58. EP250304a: Einstein Probe detection of an X-ray transient
  59. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  60. EP250302a: SAO RAS optical observations
  61. EP250302a : GIT optical follow-up
  62. EP250302a: Kinder optical follow-up observations
  63. EP250302a: Swift/UVOT detection
  64. EP250302a: optical observation from the INAF Asiago Observatory
  65. EP250302a: REM NIR upper limits
  66. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  67. EP250302a: Mondy Observations and Optical Light Curve
  68. EP250302a: VLT/MUSE optical redshift z = 1.131
  69. EP250302A: VLT near-infrared observations
  70. EP250302A: VLT/X-shooter tentative redshift
  71. EP250302a: OHP/T193 optical and spectroscopic observations
  72. EP250302a: Einstein Probe detection of an X-ray transient
  73. EP250302a: SVOM/C-GFT optical observations
  74. GRB 250226A: GRANDMA Optical Observations
  75. EP250302a: Montarrenti Observatory optical detection
  76. EP250302a: Nanshan/HMT optical counterpart detection
  77. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  78. GRB 250225B: VLT near-infrared afterglow confirmation
  79. EP250228a: Optical observations with Kinder and Swift/UVOT
  80. Konus-Wind detection of GRB 250226A
  81. GRB 250226A: KAO Optical Upper Limit
  82. GRB 250226A: AbAO AS-32 Optical Upper Limit
  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. EP250223a: J band upper limit by SYSU 80cm telescope
  90. EP250228a: Einstein Probe detection of an X-ray transient
  91. GRB 250225B: VLT/Xshooter imaging
  92. GRB 250205A / EP250205A: further radio observations with the VLA
  93. EP250225a: NOT optical candidate counterpart
  94. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  95. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  96. EP250225a: TRT optical upper limits
  97. EP250226a/GRB 250226A: 1.6m Mephisto observations
  98. EP250226a/GRB 250226A: Kinder optical follow-up observations
  99. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate

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