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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"

32689 results found.

  1. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  2. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  3. Konus-Wind detection of GRB 250222A
  4. EP250304a: REM NIR upper limits
  5. IPN triangulation of GRB 250222A
  6. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  7. EP250302a: Mondy Continued Optical Observations
  8. EP250304a: VLT/X-shooter redshift z = 0.200
  9. EP250304a: Swift-XRT detection of a fading X-ray source
  10. EP250304a: TRT optical counterpart detection
  11. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  12. EP250304a: Global MASTER-Net observations report
  13. EP250302a: SVOM/VT optical observation
  14. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  15. EP250302a: SAO RAS optical observations
  16. EP250302a : GIT optical follow-up
  17. EP250302a: VLT/X-shooter redshift confirmation
  18. EP250225a: the candidate optical counterpart is an AGN
  19. EP250302a: Kinder optical follow-up observations
  20. EP250302a: Swift/UVOT detection
  21. EP250302a: NUTTelA-TAO Early Measurments
  22. EP250302a: optical observation from the INAF Asiago Observatory
  23. EP250302a: REM NIR upper limits
  24. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  25. EP250302a: Mondy Observations and Optical Light Curve
  26. EP250302a: VLT/MUSE optical redshift z = 1.131
  27. INTEGRAL: end of scientific operations
  28. EP250302A: VLT near-infrared observations
  29. EP250302A: VLT/X-shooter tentative redshift
  30. EP250302a: OHP/T193 optical and spectroscopic observations
  31. EP250302a: Global MASTER-Net observations report
  32. EP250302a: Xinglong F60B optical observation
  33. EP250302a: Swift-XRT observations of a fading X-ray source
  34. EP250302a: Einstein Probe detection of an X-ray transient
  35. EP250302a: SVOM/C-GFT optical observations
  36. GRB 250226A: GRANDMA Optical Observations
  37. EP250302a: Montarrenti Observatory optical detection
  38. Fermi GRB 250302A: Global MASTER-Net observations report
  39. EP250302a: FTW optical and NIR detection
  40. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  41. GRB 250225B: VLT near-infrared afterglow confirmation
  42. EP250228a: Optical observations with Kinder and Swift/UVOT
  43. Konus-Wind detection of GRB 250226A
  44. GRB 250225B: EIRSAT-1 GMOD Detection
  45. GRB 250226A: KAO Optical Upper Limit
  46. GRB 250226A: AbAO AS-32 Optical Upper Limit
  47. EP250227a: Global MASTER-Net observations report
  48. EP250223A: Upper limits from Fermi-GBM Observations
  49. EP250227a: TRT optical upper limit
  50. GRB 250225B: VLT/HAWKI near-infrared observations
  51. EP250227a: Optical upper limits with Kinder observations
  52. EP250227a: NOT optical observations
  53. EP250228a: updates on the EP observations
  54. GRB 250226A: Fermi GBM Observation
  55. EP250225a: EP-FXT follow-up observation
  56. EP250223a: J band upper limit by SYSU 80cm telescope
  57. EP250228a: Swift/XRT localisation
  58. EP250228a: Global MASTER-Net observations report
  59. GRB 250226A / EP250226a: LCO detection of the afterglow
  60. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  62. GRB 250225B: VLT/Xshooter imaging
  63. GRB 250205A / EP250205A: further radio observations with the VLA
  64. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  65. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  66. GRB 250225B: INTEGRAL SPI-ACS detection
  67. EP250225a: NOT optical candidate counterpart
  68. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  69. EP250226a / GRB 250226A: SVOM/VT optical observations
  70. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  71. EP250225a: TRT optical upper limits
  72. EP250226a/GRB 250226A: 1.6m Mephisto observations
  73. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  74. EP250226a/GRB 250226A: Kinder optical follow-up observations
  75. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  76. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  77. Fermi GRB 250226B: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  79. GRB 250225B: Fermi GBM Observation
  80. GRB 250221A: ATCA Detections and Upper Limits
  81. GRB 250225B: REM NIR upper limits
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  83. Konus-Wind detection of GRB 250225B
  84. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  85. EP250223a: CrAO ZTSH optical observation
  86. GRB 250225B: VLT optical and near-infrared candidate counterpart
  87. GRB 250225B: VLT/FORS2 candidate optical afterglow
  88. GRB 250225B: SVOM/GRM observation of a long burst
  89. GRB 250226A: GECAM-B detection
  90. GRB 250221A: EP-FXT detection of the X-ray afterglow
  91. GRB 250214A: SVOM/GRM observation
  92. EP250226a/GRB 250226A: GSP detects optical counterpart
  93. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  94. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  95. EP250226a / GRB 250226A: TRT optical counterpart observation
  96. EP250226a: Global MASTER-Net observations report
  97. Swift GRB 250225B: Global MASTER-Net observations report
  98. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  99. Fermi GRB 250226A: Global MASTER-Net observations report
  100. EP250225a: Global MASTER-Net observations report

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