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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').
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28109 results found.

  1. EP250827a: confirmation of optical rebrightening with LCO
  2. GRB 250826A: SVOM/GRM observation
  3. EP250827A: An optical rebrightening was detected by LCO.
  4. EP250827a: Swift-XRT counterpart detection
  5. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  6. EP250827a: TRT optical observations
  7. EP250827a: Gemini-South redshift z = 1.613
  8. EP250827a: Einstein Probe detection of an X-ray transient
  9. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  10. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  11. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  12. Fermi GRB 250824B: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  14. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  15. GRB 250823A: Swift-BAT refined analysis
  16. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  17. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  18. GRB 250823A: Swift-XRT refined Analysis
  19. EP250821a: MeerKAT radio counterpart
  20. GRB 250823A: COLIBRÍ optical observations
  21. GRB 250823A: SVOM/VT optical observation
  22. GRB 250823A: Swift/UVOT Detection
  23. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  24. GRB 250823A: Fermi GBM Observation
  25. GRB 250823A: Enhanced Swift-XRT position
  26. GRB 250823A: LCOGT Optical Detection
  27. GRB 250823A: Swift detection of a burst
  28. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  29. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  30. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  31. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  32. GRB 250806A: Gemini observations of host galaxy candidate
  33. GRB 250821A: Kilonova-Catcher optical upper limits
  34. EP250821a: Swift/XRT counterpart fading
  35. GRB 250821A: Swift-BAT refined analysis
  36. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  37. LIGO/Virgo/KAGRA S250818k: NOT optical observations of AT2025ulz
  38. GRB 250821A: VLT/FORS2 Optical Observation
  39. GRB 250821B: SVOM/GRM observation
  40. EP250821a: SVOM/VT optical observation
  41. GRB 250821A: NOT z-band upper limit
  42. GRB 250821A: KAIT optical upper limit
  43. GRB 250821A: Swift-XRT refined Analysis
  44. GRB 250821B: Fermi GBM Detection
  45. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  46. GRB 250821A: Enhanced Swift-XRT position
  47. GRB 250821A: Swift/UVOT Upper Limits
  48. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  49. EP250821a: Swift XRT and UVOT counterpart detection
  50. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  51. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  52. GRB 250821A: LCOGT Optical Upper Limits
  53. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  54. GRB 250821A: Swift detection of a burst
  55. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  56. EP250821a: Einstein Probe detection of an X-ray transient
  57. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  58. LIGO/Virgo/KAGRA S250818k: WINTER J-band observations of AT 2025ulz
  59. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  60. GRB 250814A: Swift/UVOT Upper Limits
  61. GRB 250813B: Swift/UVOT Upper Limit
  62. IPN triangulation of GRB 250816A (short)
  63. IPN triangulation of GRB 250814C (short)
  64. IPN triangulation of GRB 250804B (short)
  65. GRB 250818B: Kilonova-Catcher optical afterglow detection
  66. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  67. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  68. LIGO/Virgo/KAGRA S250818k: Updated Sky localization and EM Bright Classification
  69. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  70. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  71. GRB 250818B: Swift/UVOT Detection
  72. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  73. GRB 250818B: SAO RAS optical observations
  74. GRB 250818A: Swift-XRT refined Analysis
  75. GRB 250818B: EP-FXT counterpart detection
  76. GRB 250818A: Swift-BAT refined analysis
  77. GRB 250818B: KAIT optical observations
  78. GRB 250818A: Swift/UVOT Upper Limits
  79. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  80. GRB 250818A: Enhanced Swift-XRT position
  81. GRB 250813B: SVOM/ECLAIRs refined analysis
  82. GRB 250818A: Fermi GBM Observation
  83. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  84. GRB 250814A: Further GRAWITA TNG NIR observations
  85. GRB 250818B: Swift-XRT afterglow detection
  86. GRB 250818B: SVOM detection of a short burst
  87. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  88. GRB 250818A: Swift detection of a burst
  89. sb25081602: Swift-XRT observations
  90. GRB 250816A: SVOM/GRM observation of a short burst
  91. GRB 250814A: Swift-BAT refined analysis
  92. GRB 250813B: Liverpool Telescope optical upper limits
  93. GRB 250814A: Further COLIBRÍ optical upper limit
  94. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  95. GRB 250814A: GRAWITA TNG NIR observations
  96. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  97. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  98. GRB250814A: TRT optical upper limits
  99. GRB 250814B: SVOM/GRM observation
  100. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources

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