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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

3039 results found.

  1. Fermi GRB 251125B: Global MASTER-Net observations report
  2. EP251118A: 3.6m DOT optical afterglow detection
  3. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  5. EP251122a: Global MASTER-Net observations report
  6. GRB 251122A / EP251122a: SVOM detection of a long burst
  7. EP251118A / GRB 251118C : MASTER optical counterpart observations
  8. EP251118a: Global MASTER-Net observations report
  9. LAT GRB251118.86: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  11. GRB 251116C: SVOM/ECLAIRs refined analysis
  12. LAT GRB251117.51: Global MASTER-Net observations report
  13. GRB 251116C: Swift/BAT arcminute localization of a burst
  14. GRB 251116C: SVOM detection of a burst
  15. GRB 251112A: Swift-BAT refined analysis
  16. Fermi GRB 251114A: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  18. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  19. GRB 251111A: SVOM/VT optical observations with X-band data
  20. GRB 251111A: SVOM/VT optical observations with VHF data
  21. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  22. Fermi trigger No 784329591: Global MASTER-Net observations report
  23. Fermi trigger No 784279167: Global MASTER-Net observations report
  24. SVOM GRB251108.54: Global MASTER-Net observations report
  25. SVOM GRB251106.83: Global MASTER-Net observations report
  26. GRB 251106A: MASTER optical observations
  27. GRB 250920C: TERI Gamma-ray detection
  28. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  29. Fermi GRB 251105A: Global MASTER-Net observations report
  30. GRB 251103A: WFST optical observations
  31. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  32. GRB 251103B: MITSuME Akeno optical upper limits
  33. Fermi GRB 251103A: Global MASTER-Net observations report
  34. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  35. GRB 251028A: MAXI/GSC detection
  36. Fermi GRB 251025C: Global MASTER-Net observations report
  37. GRB 251023A: SVOM/GRM observation
  38. EP251023b: Global MASTER-Net observations report
  39. GRB 251023A: Glowbug gamma-ray detection
  40. EP251023a: COLIBRÍ optical observations
  41. Fermi GRB 251023A: Global MASTER-Net observations report
  42. GRB 251023A: Fermi GBM Final Localization Correction
  43. EP251021b: BOOTES-7 optical upper limit
  44. GRB 250911A: MAXI/GSC detection
  45. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 251017A: COLIBRÍ optical observations of a late plateau
  47. IceCube-251018A: Global MASTER-Net observations report
  48. Fermi GRB 251016B: Global MASTER-Net observations report
  49. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  50. IceCube Alert 251014.77: Global MASTER-Net observations report
  51. GRB 251014A: Swift-BAT refined analysis
  52. GRB 251014D: Swift detection of a burst
  53. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  54. GRB 251013C: BOOTES-6 early optical detection
  55. GRB 251013A: SVOM/GRM observation
  56. GRB 250919A: TERI gamma-ray detection
  57. EP251006a: Global MASTER-Net observations report
  58. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  59. Swift GRB 251007A: Global MASTER-Net observations report
  60. GRB 251007B: SVOM detection of a faint burst
  61. GRB 250702B/EP250702a: JWST/NIRCam Observations
  62. Fermi GRB 251006B: Global MASTER-Net observations report
  63. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  64. Fermi trigger No 780609036: Global MASTER-Net observations report
  65. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  66. Fermi GRB 250926A: Global MASTER-Net observations report
  67. Konus-Wind detection of GRB 250911A
  68. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  69. GRB 250920C: Swift-BAT refined analysis
  70. GRB 250920B: Swift-BAT refined analysis
  71. GRB 250920A: Fermi GBM Final Localization
  72. Fermi GRB 250917B: Global MASTER-Net observations report
  73. GRB 250916A: GOTO optical counterpart candidate
  74. The EP-WXT trigger 01709240768 is likely a flaring star
  75. EP250911a: Global MASTER-Net observations report
  76. EP250911a: Upper limit from Fermi-GBM Observations
  77. GRB 250911A: Swift-BAT refined analysis
  78. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  79. EP#01709240653: Swift-XRT observations
  80. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  81. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  82. EP250908b: SVOM/VT optical candidate
  83. EP250908c: Global MASTER-Net observations report
  84. GRB 250903A: Swift-XRT afterglow detection
  85. IceCube Alert 250905.84: Global MASTER-Net observations report
  86. GRB 250903A: Swift/UVOT detection
  87. Swift GRB 250904A: Global MASTER-Net observations report
  88. GRB 250903A: Swift-XRT observations
  89. GRB 250903A: SVOM/VT optical confirmation with VHF data
  90. EP250901a: Mondy, Assy and SAO RAS optical limits
  91. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  92. GRB 250831A: Swift-XRT counterpart detection
  93. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  94. GRB 250830B: MAXI/GSC detection
  95. The EP-WXT trigger 01709200994 is likely a flaring star
  96. EP250828a: Global MASTER-Net observations report
  97. Fermi GRB 250827A: Global MASTER-Net observations report
  98. EP250827a: Global MASTER-Net observations report
  99. Fermi GRB 250824B: Global MASTER-Net observations report
  100. GRB 250823A: SVOM/VT optical observation

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