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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"

37264 results found.

  1. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  2. GRB 250322A: third epoch of NOT optical observations
  3. GRB 250322A: Swift-BAT refined analysis
  4. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  5. GRB 250322A: further NOT optical observations
  6. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  7. GRB 250322A: Swift/UVOT Upper Limits
  8. GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
  9. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  10. GRB 250321B: Swift-XRT observations
  11. GRB 250322A: Swift-XRT refined Analysis
  12. GRB 250322A: Gemini-North redshift of candidate host galaxy
  13. GRB 250322A: AstroSat CZTI detection of a short burst
  14. GRB 250322B: AstroSat CZTI detection of a bright long burst
  15. GRB 250322A: Gemini-South optical observations
  16. GRB 250322A: VLT optical observations
  17. GRB 250322A: VLT near-infrared observations
  18. GRB 250322A: NOT optical upper limits
  19. GRB 250322A: Enhanced Swift-XRT position
  20. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  21. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  22. GRB 250322A: MASTER optical observation
  23. EP250321a: Mondy AZT-33IK Optical Observations
  24. GRB 250322A: Swift detection of a short burst
  25. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  26. EP250321a: KAIT optical observations
  27. GRB 250225B: GECAM-A detection
  28. GRB 250312A: GECAM-A detection
  29. GRB 250321B: Swift ToO observations
  30. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  31. GRB 250321C: Fermi GBM Final Real-time Localization
  32. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  33. GRB 250320B: Fermi GBM Observation
  34. GRB 250321A: Swift-BAT refined analysis
  35. GRB 250321A: Swift-XRT refined Analysis
  36. GRB 250320B: Fermi-LAT detection
  37. GRB 250321B: SVOM detection of a sub-threshold transient event
  38. EP 250321A: Optical counterpart detection by LCO.
  39. EP250321a: Kinder optical follow-up observations
  40. GRB 250321A: Swift/UVOT Upper Limits
  41. GRB 250320B: SVOM/GRM observation of a long burst
  42. EP250321a: Swift-XRT detection of an X-ray source
  43. GRB 250320B: AstroSat CZTI detection
  44. Fermi GRB 250320B: Global MASTER-Net observations report
  45. Swift GRB 250321A: Global MASTER-Net observations report
  46. Fermi GRB 250321A: Global MASTER-Net observations report
  47. GRB 250321A: GOTO optical upper limits
  48. GRB 250321A: Swift-XRT localisation
  49. GRB 250314A: Keck/NIRC2 J-band upper limit
  50. EP250226a/GRB 250226A: KAIT optical observations
  51. GRB 250321A: Fermi GBM Observation
  52. GRB 250321A: Swift detection of a burst
  53. GRB 250321A: Fermi GBM Final Real-time Localization
  54. GRB 250320B: Fermi GBM Final Real-time Localization
  55. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  56. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  57. GRB 250320A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 250319B: Global MASTER-Net observations report
  59. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  60. GRB 250313A: GRBAlpha detection
  61. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  62. GRB 250319B: Fermi GBM Final Localization
  63. GRB 250319A: Fermi GBM Final Localization
  64. GRB 250317D: EIRSAT-1 GMOD Detection
  65. GRB 250314A: ATCA radio upper limits
  66. GRB 250317B: OHP/T193 continued follow-up
  67. GRB 250317C: SVOM/GRM observation of a long burst
  68. GRB 250317B: Leavitt Observatory optical upper limit
  69. GRB 250309B/AT2025dws: further ATCA observations
  70. GRB 250317B: Mondy AZT-33IK Optical Observations
  71. GRB 250317C: AstroSat CZTI detection
  72. GRB 250317B: NOT optical observations suggest an optical plateau phase
  73. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  74. GRB 250317C: GECAM-B detection
  75. GRB 250317B: OHP/T193 optical observations
  76. GRB250312A: Swift/UVOT Upper Limits
  77. GRB 250317B: REM optical/NIR observations
  78. GRB 250317B: Swift-XRT observations
  79. GRB 250316A: Swift/UVOT Upper Limits
  80. GRB 250314A: REM optical/NIR upper limits
  81. GRB 250316A: AbAO AS-32 Optical Upper Limit
  82. EP 250317B: Fading optical counterpart detection by LCO
  83. GRB 250316A: Swift-XRT afterglow detection
  84. GRB 250317B: LCO detection of the fading optical afterglow
  85. GRB 250317B: refined SVOM/MXT analysis
  86. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  87. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  88. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  89. GRB 250317B: SVOM detection of a burst
  90. GRB 250316A: Fermi GBM Observation
  91. GRB 250316A: Swift-XRT observations
  92. GRB 250317A: Fermi GBM Final Real-time Localization
  93. Fermi GRB 250316A: Global MASTER-Net observations report
  94. GRB 250314A: SVOM/GRM analysis
  95. GRB 250316A: Swift ToO observations
  96. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  97. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  98. GRB 250316A: Fermi GBM Final Real-time Localization
  99. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  100. GRB 250314A: EP-FXT afterglow detection

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