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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"

24927 results found.

  1. The EP-WXT trigger 01709248783 is likely a flaring star
  2. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  3. EP251118A: 3.6m DOT optical afterglow detection
  4. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  5. GRB 251122A / EP251122a: WFST optical observations
  6. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  7. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  8. GRB 251122A / EP251122a: LCO optical upper limits
  9. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  10. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  11. GRB 251122A / EP251122a: SVOM detection of a long burst
  12. EP251122a: Einstein Probe detection of an X-ray transient
  13. EP251118a: Continued Optical Detection with Kinder observations
  14. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  15. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  16. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  17. EP251118a: Xinglong-2.16m optical observation
  18. GRB 251115A: Fermi GBM Observation
  19. The EP-WXT trigger 01709248635 is likely a flaring star
  20. Fermi trigger No 785388351: Global MASTER-Net observations report
  21. EP251118A: 1.3m DFOT optical afterglow detection
  22. GRB 251118A: Swift/UVOT Detection
  23. EP251118a / GRB 251118C: SAO RAS optical observations
  24. GRB 251118A: Glowbug gamma-ray detection
  25. GRB 251118A: Fermi GBM Observation
  26. GRB 251118A: Swift-XRT afterglow detection
  27. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  28. EP251118a: Optical detection with Kinder observations
  29. GRB 251118A: GECAM-B detection
  30. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  31. The EP-WXT trigger 01709248403 is likely a flaring star
  32. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  33. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  34. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  35. GRB 251117A: Swift-XRT observations
  36. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  37. Konus-Wind detection of GRB 251118C (EP251118a)
  38. The EP-WXT trigger 01709248388 is likely a flaring star
  39. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  40. EP251118a: VLT near-infrared observation
  41. GRB 251116D: SVOM/GRM observation of a long GRB
  42. GRB 251119A: SVOM detection of a possible burst
  43. EP251118a: NOT spectroscopic redshift of z = 1.216
  44. EP251118a: NOT candidate optical counterpart
  45. EP251118a: Einstein Probe detected of a fast X-ray transient
  46. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  47. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  48. GRB 251116C: SVOM/ECLAIRs refined analysis
  49. GRB 251116B: SVOM/ECLAIRs refined analysis
  50. GRB 251114B: Insight-HXMT/HE detection
  51. GRB 251114B: GECAM-B detection of a short burst
  52. GRB 251117A: Fermi GBM observation
  53. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  54. GRB 251115A: Swift-XRT observations
  55. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  56. GRB 251117A: SVOM/GRM observation of a short burst
  57. GRB 251117A: Fermi-LAT detection
  58. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  60. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  61. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  62. GRB 251116C: Swift-XRT observations
  63. GRB 251116D: Glowbug gamma-ray detection
  64. EP251023a: Assy AZT-20 optical observations
  65. EP251023a: UAFO and AbAO optical observations
  66. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  67. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  68. GRB 251116C: SVOM/VT optical upper limit
  69. GRB 251025B: further Mondy optical observations
  70. GRB 251111A: Mondy optical upper limit
  71. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  73. GRB 251116B: LCO optical upper limits
  74. GRB 251116C: LCO optical upper limits
  75. GRB 251116C: SVOM detection of a burst
  76. GRB 251116B: SVOM detection of a burst
  77. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  78. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  79. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  80. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  81. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  82. GRB 251113A: Glowbug gamma-ray detection
  83. GRB 251113A: AstroSat CZTI detection
  84. Konus-Wind detection of GRB 251108C
  85. Konus-Wind detection of GRB 251103A
  86. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  87. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  88. The EP-WXT trigger 01709248221 is likely a flaring star
  89. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  90. GRB 251111A: SVOM/ECLAIRs refined analysis
  91. GRB 251025B: SVOM/ECLAIRs refined analysis
  92. GRB 251112A: Swift/UVOT Upper Limits
  93. GRB 251112A: Swift-XRT refined Analysis
  94. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  95. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  97. GRB 251108B: Glowbug gamma-ray detection
  98. Swift Trigger 1413695: a possible GRB 251112A
  99. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  100. GRB251111A: 1.3m DFOT optical upper limit

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