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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"

3797 results found.

  1. IceCube Alert 251225.84: Global MASTER-Net observations report
  2. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  3. GRB 251220A: MAXI/GSC detection
  4. IceCube Alert 251218.85: Global MASTER-Net observations report
  5. Fermi GRB 251217A: Global MASTER-Net observations report
  6. Fermi GRB 251215A: Global MASTER-Net observations report
  7. GRB 251214B: UAFO optical upper limit
  8. GRB 251202A: radio detection with the VLA
  9. EP251214b: Global MASTER-Net observations report
  10. GRB 251214B: LCO detection of the optical counterpart
  11. EP251214a: Global MASTER-Net observations report
  12. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 251209A: Fermi GBM observation
  14. Fermi GRB 251208C: Global MASTER-Net observations report
  15. GRB 251208B: GROWTH-India Telescope optical upper limits
  16. GRB 251208A: Fermi GBM Final Real-time Localization
  17. GRB 251205A: Liverpool Telescope further optical follow-up observations
  18. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  19. GRB 251205A: Swift detection of a burst with an optical afterglow
  20. GRB 251126B: Fermi GBM Final Localization
  21. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  22. GRB 251201A: GECAM-B observation of a burst
  23. EP251129a/GRB 251129A: NOWT Detection
  24. GRB 251201A: SVOM/GRM observation of a burst
  25. Swift GRB 251201B : MASTER optical counterpart detection
  26. Swift GRB 251201B: Global MASTER-Net observations report
  27. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  28. GRB 251201A: MAXI/GSC detection
  29. SVOM GRB 251129A : MASTER optical counterpart detection
  30. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  31. GRB 251129A: Correction to the position of the optical counterpar
  32. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. SVOM GRB251129A: Global MASTER-Net observations report
  34. GRB 251126A: Swift-BAT refined analysis
  35. GRB 251126A: Mondy and SAO RAS optical observations
  36. Fermi GRB 251125B: Global MASTER-Net observations report
  37. EP251118A: 3.6m DOT optical afterglow detection
  38. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  40. EP251122a: Global MASTER-Net observations report
  41. GRB 251122A / EP251122a: SVOM detection of a long burst
  42. EP251118A / GRB 251118C : MASTER optical counterpart observations
  43. EP251118a: Global MASTER-Net observations report
  44. LAT GRB251118.86: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  46. GRB 251116C: SVOM/ECLAIRs refined analysis
  47. LAT GRB251117.51: Global MASTER-Net observations report
  48. GRB 251116C: Swift/BAT arcminute localization of a burst
  49. GRB 251116C: SVOM detection of a burst
  50. GRB 251112A: Swift-BAT refined analysis
  51. Fermi GRB 251114A: Global MASTER-Net observations report
  52. GRB 251112B: MAXI/GSC detection
  53. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  55. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  56. GRB 251111A: SVOM/VT optical observations with X-band data
  57. GRB 251111A: SVOM/VT optical observations with VHF data
  58. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  59. Fermi trigger No 784329591: Global MASTER-Net observations report
  60. Fermi trigger No 784279167: Global MASTER-Net observations report
  61. SVOM GRB251108.54: Global MASTER-Net observations report
  62. SVOM GRB251106.83: Global MASTER-Net observations report
  63. GRB 251106A: MASTER optical observations
  64. GRB 250920C: TERI Gamma-ray detection
  65. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  66. Fermi GRB 251105A: Global MASTER-Net observations report
  67. GRB 251028A: Insight-HXMT/HE detection
  68. GRB 251103A: WFST optical observations
  69. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  70. GRB 251103B: MITSuME Akeno optical upper limits
  71. Fermi GRB 251103A: Global MASTER-Net observations report
  72. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  73. Konus-Wind detection of GRB 251028A
  74. GRB 251028A: GECAM-B detection
  75. GRB 251028A: SVOM/GRM observation
  76. GRB 251028A: Fermi GBM Observation
  77. GRB 251028A: Glowbug gamma-ray detection
  78. GRB 251028A: MAXI/GSC detection
  79. Fermi GRB 251025C: Global MASTER-Net observations report
  80. GRB 251023A: SVOM/GRM observation
  81. EP251023b: Global MASTER-Net observations report
  82. GRB 251023A: Glowbug gamma-ray detection
  83. GRB 251023B: Glowbug gamma-ray detection
  84. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  85. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  86. EP#01709247298: Swift-XRT counterpart detection
  87. EP251023a: COLIBRÍ optical observations
  88. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  89. Fermi GRB 251023A: Global MASTER-Net observations report
  90. GRB 251023A: Fermi GBM Final Localization Correction
  91. EP251021b: BOOTES-7 optical upper limit
  92. GRB 250911A: MAXI/GSC detection
  93. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 251017A: COLIBRÍ optical observations of a late plateau
  95. IceCube-251018A: Global MASTER-Net observations report
  96. Fermi GRB 251016B: Global MASTER-Net observations report
  97. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  98. IceCube Alert 251014.77: Global MASTER-Net observations report
  99. GRB 251014A: Swift-BAT refined analysis
  100. GRB 251014D: Swift detection of a burst

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