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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"

23577 results found.

  1. GRB250101A: Radio upper limits from VLA observations
  2. GRB 250305A: SVOM/GRM observation of a burst
  3. EP250302a: Optical Observations at CrAO and SAO RAS
  4. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  5. EP 250304A: Optical counterpart detection by LCO
  6. EP250302A: 1.3m DFOT optical afterglow detection
  7. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  8. EP250304a: REM NIR upper limits
  9. IPN triangulation of GRB 250222A
  10. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  11. EP250302a: Mondy Continued Optical Observations
  12. EP250304a: Swift-XRT detection of a fading X-ray source
  13. EP250304a: TRT optical counterpart detection
  14. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  15. EP250304a: Einstein Probe detection of an X-ray transient
  16. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  17. EP250302a: SAO RAS optical observations
  18. EP250302a : GIT optical follow-up
  19. EP250302a: Kinder optical follow-up observations
  20. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  21. EP250302a: Swift/UVOT detection
  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. EP250302A: VLT near-infrared observations
  28. EP250302A: VLT/X-shooter tentative redshift
  29. EP250302a: OHP/T193 optical and spectroscopic observations
  30. EP250302a: Einstein Probe detection of an X-ray transient
  31. EP250302a: SVOM/C-GFT optical observations
  32. GRB 250226A: GRANDMA Optical Observations
  33. EP250302a: Montarrenti Observatory optical detection
  34. EP250302a: Nanshan/HMT optical counterpart detection
  35. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  36. GRB 250225B: VLT near-infrared afterglow confirmation
  37. EP250228a: Optical observations with Kinder and Swift/UVOT
  38. GRB 250226A: KAO Optical Upper Limit
  39. GRB 250226A: AbAO AS-32 Optical Upper Limit
  40. EP250227a: TRT optical upper limit
  41. GRB 250225B: VLT/HAWKI near-infrared observations
  42. EP250227a: Optical upper limits with Kinder observations
  43. EP250227a: NOT optical observations
  44. EP250227a: Einstein Probe detected of a fast X-ray transient
  45. EP250228a: updates on the EP observations
  46. EP250225a: EP-FXT follow-up observation
  47. EP250223a: J band upper limit by SYSU 80cm telescope
  48. EP250228a: Einstein Probe detection of an X-ray transient
  49. GRB 250225B: VLT/Xshooter imaging
  50. GRB 250205A / EP250205A: further radio observations with the VLA
  51. GRB 250225B: INTEGRAL SPI-ACS detection
  52. EP250225a: NOT optical candidate counterpart
  53. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  54. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  55. EP250225a: TRT optical upper limits
  56. EP250226a/GRB 250226A: 1.6m Mephisto observations
  57. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  58. EP250226a/GRB 250226A: Kinder optical follow-up observations
  59. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  61. GRB 250221A: ATCA Detections and Upper Limits
  62. GRB 250225B: REM NIR upper limits
  63. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  64. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  65. EP250223a: CrAO ZTSH optical observation
  66. GRB 250225B: VLT optical and near-infrared candidate counterpart
  67. GRB 250225B: VLT/FORS2 candidate optical afterglow
  68. GRB 250225B: SVOM/GRM observation of a long burst
  69. EP250226a/GRB 250226A: GSP detects optical counterpart
  70. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  71. EP250226a / GRB 250226A: TRT optical counterpart observation
  72. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  73. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  74. EP250223a: GMG Optical Observation
  75. EP250225a: Einstein Probe detected of a fast X-ray transient
  76. GRB 250225B: Swift detection of a burst
  77. EP250223a: GROWTH-India Telescope optical observations
  78. EP250215A: J band upper limit by SYSU 80cm telescope
  79. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  80. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  81. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  82. EP250223a: Kinder optical follow-up observations
  83. GRB 250207a: ATCA Radio Upper Limits
  84. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  85. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  86. GRB 250222A: SVOM/GRM observation of a burst
  87. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  88. EP250223a: REM NIR upper limit
  89. EP250223a: TRT optical afterglow observation
  90. EP250223a: refined analysis of the EP-WXT and FXT observations
  91. EP250223a: 1.6m Mephisto and 50cm array observations
  92. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  93. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  94. EP250223a: OASDG optical observations
  95. EP250223a: NOT optical afterglow candidate
  96. EP250223a: Einstein Probe detection of an X-ray transient
  97. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  98. GRB 250221A: Optical counterpart detection by LCO.
  99. EP250220a: EP-FXT follow-up observations
  100. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits

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